Computer Networks Multiple Choice Questions & Answers (MCQs)
a) RFC
b) RCF
c) ID
d) DFC
Explanation: RFC stands for Request For Comments and they are documents that describe methods, behaviors, research, or innovations applicable to the working of the Internet.
2. In the layer hierarchy as the data packet moves from the upper to the lower layers, headers are ___________
a) Added
b) Removed
c) Rearranged
d) Modified
Explanation: Each layer adds its own header to the packet from the previous layer. For example, in the Internet layer, the IP header is added over the TCP header on the data packet that came from the transport layer.
3. The structure or format of data is called ___________
a) Syntax
b) Semantics
c) Struct
d) Formatting
Explanation: The structure and format of data are defined using syntax. Semantics defines how a particular pattern to be interpreted, and what action is to be taken based on that interpretation. In programming languages, syntax of the instructions plays a vital role in designing of the program.
4. Communication between a computer and a keyboard involves ______________ transmission.
a) Automatic
b) Half-duplex
c) Full-duplex
d) Simplex
Explanation: In simplex transmission, data flows in single direction which in this case refers to the data flowing from the keyboard to the computer. Another example would be of the mouse where the data flows from the mouse to the computer only.
5. The first Network was called ________
a) CNNET
b) NSFNET
c) ASAPNET
d) ARPANET
Explanation: ARPANET stands for Advanced Research Projects Agency Networks. It was the first network to be implemented which used the TCP/IP protocol in the year 1969.
6. A _______ is the physical path over which a message travels.
a) Path
b) Medium
c) Protocol
d) Route
Explanation: Messages travel from sender to receiver via a physical path called the medium using a set of methods/rules called protocol. Mediums can be guided (wired) or unguided (wireless).
7. Which organization has authority over interstate and international commerce in the communications field?
a) ITU-T
b) IEEE
c) FCC
d) ISOC
Explanation: FCC is the abbreviation for Federal Communications Commission. FCC is responsible for regulating all interstate communications originating or terminating in USA. It was founded in the year 1934.
8. Which of this is not a network edge device?
a) PC
b) Smartphones
c) Servers
d) Switch
Explanation: Network edge devices refer to host systems, which can host applications like web browser. A switch can’t operate as a host, but as a central device which can be used to manage network communication.
9. A _________ set of rules that governs data communication.
a) Protocols
b) Standards
c) RFCs
d) Servers
Explanation: In communications, a protocol refers to a set of rules and regulations that allow a network of nodes to transmit and receive information. Each layer in the network model has a protocol set, for example, the transport layer has TCP and UDP protocols.
10. Three or more devices share a link in ________ connection.
a) Unipoint
b) Multipoint
c) Point to point
d) Simplex
Explanation: A multipoint communication is established when three or many network nodes are connected to each other. Frame relay, Ethernet and ATM are some examples of multipoint connections.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “Reference Models – 1”.
1. How many layers are present in the Internet protocol stack (TCP/IP model)?
a) 5
b) 7
c) 6
d) 10
Explanation: There are five layers in the Internet Protocol stack. The five layers in Internet Protocol stack is Application, Transport, Network, Data link and Physical layer. The internet protocol stack model is also called the TCP/IP model and it’s used in modern Internet Communication.
2. The number of layers in ISO OSI reference model is __________
a) 5
b) 7
c) 6
d) 10
Explanation: The seven layers in ISO OSI reference model is Application, Presentation, Session, Transport, Network, Data link and Physical layer. OSI stands for Open System Interconnect and it is a generalized model.
3. Which of the following layers is an addition to OSI model when compared with TCP IP model?
a) Application layer
b) Presentation layer
c) Session layer
d) Session and Presentation layer
Explanation: The only difference between OSI model and TCP/IP model is that the functions of Presentation and Session layer in the OSI model are handled by the transport layer itself in TCP/IP. OSI is a generalized model and TCP/IP is an application specific model.
4. Application layer is implemented in ____________
a) End system
b) NIC
c) Ethernet
d) Packet transport
Explanation: Not only application layer, but presentation layer, session layer and transport layer are also implemented in the end system. The layers below are implemented outside the end system, for example, the network layer is implemented on the routers and the physical layer is implemented for the medium.
5. Transport layer is implemented in ______________
a) End system
b) NIC
c) Ethernet
d) Signal transmission
Explanation: Application, Presentation, Session and Transport layer are implemented in the end system. The transport layer handles the process to process delivery of the packet through ports.
6. The functionalities of the presentation layer include ____________
a) Data compression
b) Data encryption
c) Data description
d) All of the mentioned
Explanation: Some functions of the presentation layer include character-code translation, data conversion, data encryption and decryption, and data translation. It connects the application layer with the layers below converting the human readable text and media to machine readable format and vice-versa.
7. Delimiting and synchronization of data exchange is provided by __________
a) Application layer
b) Session layer
c) Transport layer
d) Link layer
Explanation: The session layer provides the mechanism for opening, closing and managing a session between end-user application processes. The session layer 5 is responsible for establishing managing synchronizing and terminating sessions. In TCP/IP protocol stack, the functions of the session layer are handled by the transport layer itself and thus the session layer is missing from the TCP/IP model.
8. In OSI model, when data is sent from device A to device B, the 5th layer to receive data at B is _________
a) Application layer
b) Transport layer
c) Link layer
d) Session layer
Explanation: In OSI reference model, the fifth layer is Session layer. Session layer provides the mechanism for opening, closing and managing a session between end-user application processes. In TCP/IP protocol stack, the functions of the session layer are handled by the transport layer itself and thus the session layer is missing from the TCP/IP model.
9. In TCP IP Model, when data is sent from device A to device B, the 5th layer to receive data at B is ____________
a) Application layer
b) Transport layer
c) Link layer
d) Session layer
Explanation: In TCP/IP model, the fifth layer is application layer. When data is sent from device A to device B, the 5th layer to receive data at B is application layer. Application layer provides the interface between applications and the network. The user interacts with only this layer.
10. In the OSI model, as a data packet moves from the lower to the upper layers, headers are _______
a) Added
b) Removed
c) Rearranged
d) Randomized
Explanation: In OSI reference model, when data packet moves from lower layers to higher layer, headers get removed. Whereas when the data packet moves from higher layer to lower layers, headers are added. These headers contain the essential control information for the protocols used on the specific layer.
11. Which of the following statements can be associated with OSI model?
a) A structured way to discuss and easier update system components
b) One layer may duplicate lower layer functionality
c) Functionality at one layer no way requires information from another layer
d) It is an application specific network model
Explanation: One layer may use the information from another layer, for example timestamp value. The information is contained in the header inserted by the previous layer. The headers are added as the packet moves from higher layers to the lower layers.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “Physical Layer”.
1. The physical layer is concerned with ___________
a) bit-by-bit delivery
p) process to process delivery
c) application to application delivery
d) port to port delivery
Explanation: Physical layer deals with bit to bit delivery in networking. The data unit in the physical layer is bits. Process to process delivery or the port to port delivery is dealt in the transport layer. The various transmission mediums aid the physical layer in performing its functions.
2. Which transmission media provides the highest transmission speed in a network?
a) coaxial cable
b) twisted pair cable
c) optical fiber
d) electrical cable
Explanation: Fiber optics is considered to have the highest transmission speed among the all mentioned above. The fiber optics transmission runs at 1000Mb/s. It is called as 1000Base-Lx whereas IEEE standard for it is 802.3z. It is popularly used for modern day network connections due to its high transmission rate.
3. Bits can be sent over guided and unguided media as analog signal by ___________
a) digital modulation
b) amplitude modulation
c) frequency modulation
d) phase modulation
Explanation: In analog modulation, digital low frequency baseband signal (digital bit stream) is transmitted over a higher frequency. Whereas in digital modulation the only difference is that the base band signal is of discrete amplitude level. The bits are represented by only two frequency levels, one for high and one for low.
4. The portion of physical layer that interfaces with the media access control sublayer is called ___________
a) physical signalling sublayer
b) physical data sublayer
c) physical address sublayer
d) physical transport sublayer
Explanation: The portion of physical layer that interfaces with the medium access control sublayer is Physical Signaling Sublayer. The main function of this layer is character encoding, reception, decoding and performs optional isolation functions. It handles which media connection the signal should be forwarded to physically.
5. The physical layer provides __________
a) mechanical specifications of electrical connectors and cables
b) electrical specification of transmission line signal level
c) specification for IR over optical fiber
d) all of the mentioned
Explanation: Anything dealing with a network cable or the standards in use – including pins, connectors and the electric current used is dealt in the physical layer (Layer 1). Physical layer deals with bit to bit delivery of the data aided by the various transmission mediums.
6. In asynchronous serial communication the physical layer provides ___________
a) start and stop signalling
b) flow control
c) both start & stop signalling and flow control
d) only start signalling
Explanation: In asynchronous serial communication, the communication is not synchronized by clock signal. Instead of a start and stop signaling and flow control method is followed. Unlike asynchronous serial communication, in synchronous serial communication a clock signal is used for communication, so the start and stop method is not really required.
7. The physical layer is responsible for __________
a) line coding
b) channel coding
c) modulation
d) all of the mentioned
Explanation: The physical layer is responsible for line coding, channel coding and modulation that is needed for the transmission of the information. The physical configuration including pins, connectors and the electric current used is dealt in the physical layer based on the requirement of the network application.
8. The physical layer translates logical communication requests from the ______ into hardware specific operations.
a) data link layer
b) network layer
c) trasnport layer
d) application layer
Explanation: Physical layer accepts data or information from the data link layer and converts it into hardware specific operations so as to transfer the message through physical cables. Some examples of the cables used are optical fiber cables, twisted pair cables and co-axial cables.
9. A single channel is shared by multiple signals by ____________
a) analog modulation
b) digital modulation
c) multiplexing
d) phase modulation
Explanation: In communication and computer networks, the main goal is to share a scarce resource. This is done by multiplexing, where multiple analog or digital signals are combined into one signal over a shared medium. The multiple kinds of signals are designated by the transport layer which is the layer present on a higher level than the physical layer.
10. Wireless transmission of signals can be done via ___________
a) radio waves
b) microwaves
c) infrared
d) all of the mentioned
Explanation: Wireless transmission is carried out by radio waves, microwaves and IR waves. These waves range from 3 Khz to above 300 Ghz and are more suitable for wireless transmission. Radio waves can penetrate through walls and are used in radio communications, microwaves and infrared (IR) waves cannot penetrate through walls and are used for satellite communications and device communications respectively.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “Network Layer”.
1. The network layer is concerned with __________ of data.
a) bits
b) frames
c) packets
d) bytes
Explanation: In computer networks, the data from the application layer is sent to the transport layer and is converted to segments. These segments are then transferred to the network layer and these are called packets. These packets are then sent to data link layer where they are encapsulated into frames. These frames are then transferred to physical layer where the frames are converted to bits.
2. Which one of the following is not a function of network layer?
a) routing
b) inter-networking
c) congestion control
d) error control
Explanation: In the OSI model, network layer is the third layer and it provides data routing paths for network communications. Error control is a function of the data link layer and the transport layer.
3. A 4 byte IP address consists of __________
a) only network address
b) only host address
c) network address & host address
d) network address & MAC address
Explanation: An ip address which is 32 bits long, that means it is of 4 bytes and is composed of a network and host portion and it depends on address class. The size of the host address and network address depends upon the class of the address in classful IP addressing.
4. In virtual circuit network each packet contains ___________
a) full source and destination address
b) a short VC number
c) only source address
d) only destination address
Explanation: A short VC number also called as VCID (virtual circuit identifier) is a type of identifier which is used to distinguish between several virtual circuits in a connection oriented circuit switched network. Each virtual circuit is used to transfer data over a larger packet switched network.
5. Which of the following routing algorithms can be used for network layer design?
a) shortest path algorithm
b) distance vector routing
c) link state routing
d) all of the mentioned
Explanation: The routing algorithm is what decides where a packet should go next. There are several routing techniques like shortest path algorithm, static and dynamic routing, decentralized routing, distance vector routing, link state routing, Hierarchical routing etc. The routing algorithms go hand in hand with the operations of all the routers in the networks. The routers are the main participants in these algorithms.
6. Which of the following is not correct in relation to multi-destination routing?
a) is same as broadcast routing
b) contains the list of all destinations
c) data is not sent by packets
d) there are multiple receivers
Explanation: In multi-destination routing, there is more than one receiver and the route for each destination which is contained in a list of destinations is to be found by the routing algorithm. Multi-destination routing is also used in broadcasting.
7. A subset of a network that includes all the routers but contains no loops is called ________
a) spanning tree
b) spider structure
c) spider tree
d) special tree
Explanation: Spanning tree protocol (STP) is a network protocol that creates a loop free logical topology for ethernet networks. It is a layer 2 protocol that runs on bridges and switches. The main purpose of STP is to ensure that you do not create loops when you have redundant paths in your network.
8. Which one of the following algorithm is not used for congestion control?
a) traffic aware routing
b) admission control
c) load shedding
d) routing information protocol
Explanation: The Routing Information Protocol (RIP) is used by the network layer for the function of dynamic routing. Congestion control focuses on the flow of the traffic in the network and uses algorithms like traffic aware routing, admission control and load shedding to deal with congestion.
9. The network layer protocol for internet is __________
a) ethernet
b) internet protocol
c) hypertext transfer protocol
d) file transfer protocol
Explanation: There are several protocols used in Network layer. Some of them are IP, ICMP, CLNP, ARP, IPX, HRSP etc. Hypertext transfer protocol is for application layer and ethernet protocol is for data link layer.
10. ICMP is primarily used for __________
a) error and diagnostic functions
b) addressing
c) forwarding
d) routing
Explanation: ICMP abbreviation for Internet Control Message Protocol is used by networking devices to send error messages and operational information indicating a host or router cannot be reached. ICMP operates over the IP packet to provide error reporting functionality as IP by itself cannot report errors.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “Topology”.
1. Physical or logical arrangement of network is __________
a) Topology
b) Routing
c) Networking
d) Control
Explanation: Topology in networks is the structure or pattern in which each and every node in the network is connected. There are many topologies in networking like bus, tree, ring, star, mesh, and hybrid topology. There is no particular best topology and a suitable topology can be chosen based on the kind of application of the network .
2. Which network topology requires a central controller or hub?
a) Star
b) Mesh
c) Ring
d) Bus
Explanation: In star topology, no computer is connected to another computer directly but all the computers are connected to a central hub. Every message sent from a source computer goes through the hub and the hub then forwards the message only to the intended destination computer.
3. _______ topology requires a multipoint connection.
a) Star
b) Mesh
c) Ring
d) Bus
Explanation: In bus topology, there is a single cable to which all the network nodes are connected. So whenever a node tries to send a message or data to other nodes, this data passes through all other nodes in the network through the cable. It is really simple to install but it’s not secure enough to be used in most of the computer network applications.
4. Data communication system spanning states, countries, or the whole world is ________
a) LAN
b) WAN
c) MAN
d) PAN
Explanation: WAN is the abbreviation for Wide Area Network. This network extends over a large geographical area. WANs are used to connect cities, states or even countries. A wireless connection is required to build a WAN. The best example of WAN is the Internet.
5. Data communication system within a building or campus is________
a) LAN
b) WAN
c) MAN
d) PAN
Explanation: LAN is an abbreviation for Local Area Network. This network interconnects computers in a small area such as schools, offices, residence etc. It is the most versatile kind of data communication system where most of the computer network concepts can be visibly used.
6. WAN stands for __________
a) World area network
b) Wide area network
c) Web area network
d) Web access network
Explanation: WAN is the abbreviation for Wide Area Network. This network extends over a large geographical area. These are used to connect cities, states or even countries. They can be connected through leased lines or satellites.
7. In TDM, slots are further divided into __________
a) Seconds
b) Frames
c) Packets
d) Bits
Explanation: TDM is the abbreviation for Time division multiplexing. It is technique for combining several low rate channels to a single high rate channel. For a certain time slot, the several channels could use the maximum bandwidth. Each channel is inactive for a period of time too. Some other multiplexing techniques are Frequency division multiplexing and Phase division multiplexing.
8. _____ is the multiplexing technique that shifts each signal to a different carrier frequency.
a) FDM
b) TDM
c) Both FDM & TDM
d) PDM
Explanation: FDM is an abbreviation for Frequency Division Multiplexing. This technique is used when the bandwidth of the channel is greater than the combined bandwidth of all the signals which are to be transmitted. The channel is active at all times unless a collision occurs with another channel trying to use the same frequency. Some other multiplexing techniques are Time division multiplexing and Phase division multiplexing.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “Network Attacks”.
1. The attacker using a network of compromised devices is known as _____________
a) Internet
b) Botnet
c) Telnet
d) D-net
Explanation: Botnet is a network of compromised devices used by the attacker without the owner’s knowledge to perform unethical activities such as spamming. The attacker usually uses the least secure devices to create the botnet.
2. Which of the following is a form of DoS attack?
a) Vulnerability attack
b) Bandwidth flooding
c) Connection flooding
d) All of the mentioned
Explanation: In a DoS attack, the attacker won’t let the victims access the network by using a certain method that ensures that an essential network resource is unavailable to the victim. In vulnerability attack, the attacker exploits any obvious vulnerable entity in the network to deny the victim access into the network. In bandwidth flooding, the attacker floods the victim with a huge flow of packets and uses up all the bandwidth. In connection flooding, the attacker floods the victim network with a huge number of connections, so that, no other machine can connect to it.
3. The DoS attack, in which the attacker establishes a large number
of half-open or fully open TCP connections at the target host is
________
a) Vulnerability attack
b) Bandwidth flooding
c) Connection flooding
d) UDP flooding
Explanation: In Vulnerability attack, the attacker exploits the vulnerable control points of the network to deny access to the victims. In Bandwidth flooding, the attacker intentionally uses up all the bandwidth by flooding the victim with a deluge of packets and makes sure that the victim can’t use any bandwidth. In UDP flooding, too many UDP packets are sent by the attacker to the victim at random ports.
4. The DoS attack, in which the attacker sends deluge of packets to the targeted host is ________
a) Vulnerability attack
b) Bandwidth flooding
c) Connection flooding
d) UDP flooding
Explanation: In Bandwidth flooding, the attacker floods the victim machine with a deluge of packets to make sure that no bandwidth is available. The victim then cannot utilize the complete bandwidth to perform its operation.
5. Packet sniffers involve ____________
a) Active receiver
b) Passive receiver
c) Legal receiver
d) Partially-active receiver
Explanation: The function of packet sniffers is to just silently receive the packets flowing in the channel. If they inject any packets into the channel, they might alert the other users about the intrusion.
6. Sniffers can be prevented by using _______________
a) Wired environment
b) WiFi
c) Ethernet LAN
d) Switched network
Explanation: Switches make sure that the packet is sent to the intended receiver and no one else, thus preventing Sniffers to perform their function. Intelligent switches are hence used preferably for the network.
7. Firewalls are often configured to block ___________
a) UDP traffic
b) TCP traffic
c) Sensitive traffic
d) Best-effort traffic
Explanation: UDP is more vulnerable to attacks, so firewalls are often configured to block suspicious UDP traffic.
8. In a network, If P is the only packet being transmitted and there
was no earlier transmission, which of the following delays could be
zero?
a) Propagation delay
b) Queuing delay
c) Transmission delay
d) Processing delay
Explanation: Since there is no other packet to be transmitted, there is no need for a queue. Therefore, the delay caused due to the queuing would be none i.e. 0.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “Application Layer – 1”.
1. Which is not a application layer protocol?
a) HTTP
b) SMTP
c) FTP
d) TCP
Explanation: TCP is transport layer protocol.
2. The packet of information at the application layer is called __________
a) Packet
b) Message
c) Segment
d) Frame
Explanation: For Application, Presentation and Session layers there is no data format for message. Message is message as such in these three layers. But when it comes to Transport, Network, Data and Physical layer they have data in format of segments, packets, frames and bits respectively.
3. Which one of the following is an architecture paradigms?
a) Peer to peer
b) Client-server
c) HTTP
d) Both Peer-to-Peer & Client-Server
Explanation: HTTP is a protocol.
4. Application developer has permission to decide the following on transport layer side
a) Transport layer protocol
b) Maximum buffer size
c) Both Transport layer protocol and Maximum buffer size
d) None of the mentioned
Explanation: Application layer provides the interface between applications and the network. So application developer can decide what transport layer to use and what should be its maximum buffer size.
5. Application layer offers _______ service.
a) End to end
b) Process to process
c) Both End to end and Process to process
d) None of the mentioned
Explanation: End to End service is provided in the application layer. Whereas process to process service is provided at the transport layer.
6. E-mail is _________
a) Loss-tolerant application
b) Bandwidth-sensitive application
c) Elastic application
d) None of the mentioned
Explanation: Because it can work with available throughput.
7. Pick the odd one out.
a) File transfer
b) File download
c) E-mail
d) Interactive games
Explanation: File transfer, File download and Email are services provided by the application layer and there are message and data oriented.
8. Which of the following is an application layer service?
a) Network virtual terminal
b) File transfer, access, and management
c) Mail service
d) All of the mentioned
Explanation: The services provided by the application layer are network virtual terminal, file transfer, access and management, mail services, directory services, various file and data operations.
9. To deliver a message to the correct application program running on a host, the _______ address must be consulted.
a) IP
b) MAC
c) Port
d) None of the mentioned
Explanation: IP address lets you know where the network is located. Whereas MAC address is a unique address for every device. Port address identifies a process or service you want to carry on.
10. Which is a time-sensitive service?
a) File transfer
b) File download
c) E-mail
d) Internet telephony
Explanation: Internet telephony is Loss-tolerant other applications are not.
Explanation: The transport services that are provided to application are reliable data transfer, security and timing. These are very important for proper end to end services.
12. Electronic mail uses which Application layer protocol?
a) SMTP
b) HTTP
c) FTP
d) SIP
Explanation: Email uses various protocols like SMTP, IMAP and POP. The most prominent one used in application layer is SMTP.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “SSH”.
1. Secure shell (SSH) network protocol is used for __________
a) secure data communication
b) remote command-line login
c) remote command execution
d) all of the mentioned
Explanation: SSH provides high encryption and security features while communicating through a network. It is a cryptographic network protocol.
2. SSH can be used in only _____________
a) unix-like operating systems
b) windows
c) both unix-like and windows systems
d) none of the mentioned
Explanation: SSH isn’t confined to a certain network or operating system. It can be implemented over different networks and on different operating systems.
3. SSH uses ___________ to authenticate the remote computer.
a) public-key cryptography
b) private-key cryptography
c) any of public-key or private-key
d) both public-key & private-key
Explanation: Public encryption key is slower but more flexible. Every cryptographic security system requires a private key for private access and a public key for location.
4. Which standard TCP port is assigned for contacting SSH servers?
a) port 21
b) port 22
c) port 23
d) port 24
Explanation: Port 22 is used for contacting ssh servers, used for file transfers (scp, sftp) and also port forwarding.
5. Which one of the following protocol can be used for login to a shell on a remote host except SSH?
a) telnet
b) rlogin
c) both telnet and rlogin
d) none of the mentioned
Explanation: SSH is more secured then telnet and rlogin.
6. Which one of the following is a file transfer protocol using SSH?
a) SCP
b) SFTP
c) Rsync
d) All of the mentioned
Explanation: SCP (Secure copy protocol), SFTP (SSH File Transfer Protocol) and Rsync all are file transfer protocols which are used by SSH.
7. SSH-2 does not contain ______________
a) transport layer
b) user authentication layer
c) physical layer
d) connection layer
Explanation: SSH2 is a more secure, portable and efficient version of SSH that includes SFTP, which is functionally similar to FTP, but is SSH2 encrypted.
8. Which one of the following feature was present in SSH protocol, version 1?
a) password changing
b) periodic replacement of session keys
c) support for public-key certificates
d) none of the mentioned
Explanation: All of the mentioned features are provided by SSH-2 and that SSH-1 only provide strong authentication and guarantee confidentiality.
9. SCP protocol is evolved from __________ over SSH.
a) RCP protocol
b) DHCP protocol
c) MGCP protocol
d) GCP protocol
Explanation: RCP is the abbreviation for Rate Control Protocol is a congestion control algorithm for fast user response times.
10. Which one of the following authentication method is used by SSH?
a) public-key
b) host based
c) password
d) all of the mentioned
Explanation: SSH used public key authentication, Password authentication, Host based authentication, keyboard authentication and authentication of servers.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “TCP-1”.
1. Which of the following is false with respect to TCP?
a) Connection-oriented
b) Process-to-process
c) Transport layer protocol
d) Unreliable
Explanation: TCP is a transport layer protocol that provides reliable and ordered delivery of a stream of bytes between hosts communicating via an IP network.
2. In TCP, sending and receiving data is done as _______
a) Stream of bytes
b) Sequence of characters
c) Lines of data
d) Packets
Explanation: TCP provides stream oriented delivery between hosts communicating via an IP network and there are no message boundaries. TCP can concatenate data from a number of send () commands into one stream of data and still transmit it reliably.
3. TCP process may not write and read data at the same speed. So we need __________ for storage.
a) Packets
b) Buffers
c) Segments
d) Stacks
Explanation: A TCP receiver has a receive buffer that is used to store the unprocessed incoming packets in case the sender is sending packets faster than the processing rate of the received packets.
4. TCP groups a number of bytes together into a packet called _______
a) Packet
b) Buffer
c) Segment
d) Stack
Explanation: A segment may be collection of data from many send () statements. TCP transmits each segment as a stream of bytes.
5. Communication offered by TCP is ________
a) Full-duplex
b) Half-duplex
c) Semi-duplex
d) Byte by byte
Explanation: Data can flow both the directions at the same time during a TCP communication hence, it is full-duplex. This is the reason why TCP is used in systems that require full-duplex operation such as e-mail systems.
6. To achieve reliable transport in TCP, ___________ is used to check the safe and sound arrival of data.
a) Packet
b) Buffer
c) Segment
d) Acknowledgment
Explanation: Acknowledgment mechanism is used to check the safe and sound arrival of data. The sender actively checks for acknowledgement from the receiver and once a specific time period has passed, it retransmits the data.
7. In segment header, sequence number and acknowledgement number fields refer to _______
a) Byte number
b) Buffer number
c) Segment number
d) Acknowledgment
Explanation: As TCP has to ensure ordered delivery of packets, sequence number and acknowledgement number are used to identify the byte number of the packet in the stream of bytes being transmitted.
8. Suppose a TCP connection is transferring a file of 1000 bytes. The
first byte is numbered 10001. What is the sequence number of the
segment if all data is sent in only one segment?
a) 10000
b) 10001
c) 12001
d) 11001
Explanation: The sequence number given to first byte of a segment, with respect to its order among the previous segments, is the sequence number of that segment.
9. Bytes of data being transferred in each connection are numbered by TCP. These numbers start with a _________
a) Fixed number
b) Random sequence of 0’s and 1’s
c) One
d) Sequence of zero’s and one’s
Explanation: One might expect the sequence number of the first byte in the stream to be 0, or 1. But that does not happen in TCP, Instead, the sender has to choose an Initial Sequence Number (ISN), which is basically a random 32 bit sequence of 0’s and 1’s, during the connection handshake.
10. The value of acknowledgement field in a segment defines _______
a) sequence number of the byte received previously
b) total number of bytes to receive
c) sequence number of the next byte to be received
d) sequence of zeros and ones
Explanation: The acknowledgement field in a segment defines the sequence number of the byte which is to be received next i.e. sequence number of byte that the sender should transmit next.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “UDP”.
1. Which of the following is false with respect to UDP?
a) Connection-oriented
b) Unreliable
c) Transport layer protocol
d) Low overhead
Explanation: UDP is an unreliable, connectionless transport layer protocol that provides message-based data transmission. TCP is an example of connection-oriented protocols.
2. Return value of the UDP port “Chargen” is _______
a) String of characters
b) String of integers
c) Array of characters with integers
d) Array of zero’s and one’s
Explanation: Using Chargen with UDP on port 19, the server sends a UDP datagram containing a random number of characters every time it receives a datagram from the connecting host. The number of characters is between 0 and 512.
3. Beyond IP, UDP provides additional services such as _______
a) Routing and switching
b) Sending and receiving of packets
c) Multiplexing and demultiplexing
d) Demultiplexing and error checking
Explanation: De-multiplexing is the delivering of received segments to the correct application layer processes at the recipients end using UDP. Error checking is done through checksum in UDP.
4. What is the main advantage of UDP?
a) More overload
b) Reliable
c) Low overhead
d) Fast
Explanation: As UDP does not provide assurance of delivery of packet, reliability and other services, the overhead taken to provide these services is reduced in UDP’s operation. Thus, UDP provides low overhead, and higher speed.
5. Port number used by Network Time Protocol (NTP) with UDP is ________
a) 161
b) 123
c) 162
d) 124
Explanation: The Network Time Protocol is a clock synchronization network protocol implemented by using UDP port number 123 to send and receive time stamps.
6. What is the header size of a UDP packet?
a) 8 bytes
b) 8 bits
c) 16 bytes
d) 124 bytes
Explanation: The fixed size of the UDP packet header is 8 bytes. It contains four two-byte fields: Source port address, Destination port address, Length of packet, and checksum.
7. The port number is “ephemeral port number”, if the source host is _______
a) NTP
b) Echo
c) Server
d) Client
Explanation: Port numbers from 1025 to 5000 are used as ephemeral port numbers in Windows Operating System. Ephemeral port numbers are short-lived port numbers which can be used for clients in a UDP system where there are temporary clients all the time.
8. “Total length” field in UDP packet header is the length of _________
a) Only UDP header
b) Only data
c) Only checksum
d) UDP header plus data
Explanation: Total length is the 16 bit field which contains the length of UDP header and the data. The maximum value of the Total length field and the maximum size of a UDP datagram is 65,535 bytes (8 byte header + 65,527 bytes of data).
9. Which is the correct expression for the length of UDP datagram?
a) UDP length = IP length – IP header’s length
b) UDP length = UDP length – UDP header’s length
c) UDP length = IP length + IP header’s length
d) UDP length = UDP length + UDP header’s length
Explanation: A user datagram is encapsulated in an IP datagram. There is a field in the IP header that defines the total length of the IP packet. There is another field in the IP header that defines the length of the header. So if we subtract the length of the IP header that is encapsulated in the IP packet, we get the length of UDP datagram.
10. The ______ field is used to detect errors over the entire user datagram.
a) udp header
b) checksum
c) source port
d) destination port
Explanation: Checksum field is used to detect errors over the entire user datagram. Though it is not as efficient as CRC which is used in TCP, it gets the job done for the UDP datagram as UDP doesn’t have to ensure the delivery of the packet.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “Congestion Control”.
1. Two broad categories of congestion control are
a) Open-loop and Closed-loop
b) Open-control and Closed-control
c) Active control and Passive control
d) Active loop and Passive loop
Explanation: Open loop congestion control techniques are used to prevent congestion before it even happens by enforcing certain policies. Closed loop congestion control techniques are used to treat congestion after it has happened.
2. In open-loop control, policies are applied to __________
a) Remove after congestion occurs
b) Remove after sometime
c) Prevent before congestion occurs
d) Prevent before sending packets
Explanation: Open loop congestion control techniques are used to prevent congestion before it even happens by enforcing certain policies. Retransmission policy, window policy and acknowledgement policy are some policies that might be enforced.
3. Retransmission of packets must not be done when _______
a) Packet is lost
b) Packet is corrupted
c) Packet is needed
d) Packet is error-free
Explanation: Retransmission refers to the sender having to resend the packet to the receiver. It needs to be done only when some anomaly occurs with the packet like when the packet is lost or corrupted.
4. In Go-Back-N window, when the timer of the packet times out,
several packets have to be resent even some may have arrived safe.
Whereas in Selective Repeat window, the sender resends ___________
a) Packet which are not lost
b) Only those packets which are lost or corrupted
c) Packet from starting
d) All the packets
Explanation: In Selective Repeat, the sender side uses a searching algorithm to find the packets which need to be retransmitted based on the negative acknowledgements received and then resends only those packets thus saving bandwidth.
5. Discarding policy is mainly done by _______
a) Sender
b) Receiver
c) Router
d) Switch
Explanation: The discarding policy adopted by the routers mainly states that the routers discard sensitive or corrupted packets that it receives, thus controlling the integrity of the packet flow. The discarding policy is adopted as an open loop congestion control technique.
6. Closed-Loop control mechanisms try to _________
a) Remove after congestion occurs
b) Remove after sometime
c) Prevent before congestion occurs
d) Prevent before sending packets
Explanation: In closed loop congestion control, methods are implemented to remove congestion after it occurs. Some of the methods used are backpressure and choke packet.
7. The technique in which a congested node stops receiving data from the immediate upstream node or nodes is called as _______
a) Admission policy
b) Backpressure
c) Forward signaling
d) Backward signaling
Explanation: In this closed loop congestion control technique, the congested node propagates in the opposite direction of the data flow to inform the predecessor node to reduce the flow of packets. This is why this technique is called a node-to-node congestion control technique.
8. Backpressure technique can be applied only to _______
a) Congestion networks
b) Closed circuit networks
c) Open circuit networks
d) Virtual circuit networks
Explanation: In Virtual circuit networks, each node knows the upstream node from which a flow data is coming. So, it makes possible for the congested node to track the source of the congestion and then inform that node to reduce the flow to remove congestion.
9. The packet sent by a node to the source to inform it of congestion is called _______
a) Explicit
b) Discard
c) Choke
d) Backpressure
Explanation: Choke packet is sent by a node to the source to inform it of congestion. Two choke packet techniques can be used for the operation called hop-by-hop choke packet and source choke packet.
10. In the slow-start algorithm, the size of the congestion window increases __________ until it reaches a threshold.
a) exponentially
b) additively
c) multiplicatively
d) suddenly
Explanation: In slow-start algorithm, the size of the congestion window increases exponentially until it reaches a threshold. When it reaches the threshold, it stops increasing and continues sending packets through the threshold window thus preventing congestion.
11. In the congestion avoidance algorithm, the size of the
congestion window increases ____________ until congestion is detected.
a) exponentially
b) additively
c) multiplicatively
d) suddenly
Explanation: In the congestion avoidance algorithm, the size of the congestion window increases additively until congestion is detected. Once congestion is detected, the size of congestion window is decreased once and then the packets are transmitted to achieve congestion avoidance.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “ATM & Frame Relay”.
1. ATM and frame relay are ________
a) virtual circuit networks
b) datagram networks
c) virtual private networks
d) virtual public networks
Explanation: ATM and frame relay are transmission modes in which information is transferred through electric circuit layer as packets. ATM has fixed packet size and frame relay has variable packet size.
2. ATM uses _______________
a) asynchronous frequency division multiplexing
b) asynchronous time division multiplexing
c) asynchronous space division multiplexing
d) asynchronous amplitude division multiplexing
Explanation: ATM uses a constant data stream consisting of transmission cells to transmit information in a fixed division of time. The packet size remains fixed.
3. ATM standard defines _______ layers.
a) 2
b) 3
c) 4
d) 5
Explanation: The three layers are physical layer, ATM layer and application adoption layer. The physical layer corresponds to the physical layer, ATM layer corresponds to the data link layer and the AAL layer corresponds to the network layer of the OSI model.
4. ATM can be used for ________
a) local area network
b) wide area network
c) campus area network
d) networks covering any range
Explanation: ATM is a connection oriented network for cell relay which can be implemented for networks covering any area. It uses Time Division Multiplexing and supports voice, video and data communications.
5. An ATM cell has the payload field of __________
a) 32 bytes
b) 48 bytes
c) 64 bytes
d) 128 bytes
Explanation: An ATM field contains a header and a payload. The header is of 5 bytes and the payload is of 48 bytes. The size of the header remains fixed.
6. Frame relay has error detection at the ______
a) physical layer
b) data link layer
c) network layer
d) transport layer
Explanation: The Frame Relay header contains an 8-bit Header Error Control field (HEC). The HEC field contains an 8-bit CRC which is used for error control.
7. Virtual circuit identifier in frame relay is called ______
a) data link connection identifier
b) frame relay identifier
c) cell relay identifier
d) circuit connection identifier
Explanation: The Data Link Connection Identifier is 10-bit virtual circuit identifier. It is used to assign frames to the specified Permanent Virtual Circuits or Switched Virtual Circuits.
8. Frame relay has _______
a) only physical layer
b) only data link layer
c) only network layer
d) both physical and data link layer
Explanation: The physical layer is guided by the protocols recognized by the ANSI. The data link layer supports the simplified core functions specified by the OSI model.
9. In frame relay networks, extended address is used _______
a) to increase the range of data link connection identifiers
b) for error detection
c) for encryption
d) for error recovery
Explanation: Extended address is indicated by the last bit of every address byte in the DLCI. It specifies whether the byte is the last in the addressing field. It is used to increase the range of data link connection identifiers.
10. What is FRAD in frame relay network?
a) FRAD assembles and disassembles the frames coming from other protocols
b) FRAD is used for modulation and demodulation
c) FRAD is used for error detection
d) FRAD is used for error recovery
Explanation: FRAD stands for Frame Relay Assembler/Disassembler. It converts packets into frames that can be transmitted over Frame Relay Networks. It operates at the physical layer.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “World Wide Web”.
1. A piece of icon or image on a web page associated with another webpage is called ______
a) url
b) hyperlink
c) plugin
d) extension
Explanation: URLs are locators for resources present on the World Wide Web. A plugin provides extra functionality to the webpage. An extension provides modification allowance for the core functionality of a webpage. Hyperlink is piece of icon or image on a web page associated with another webpage.
2. Dynamic web page ______
a) is same every time whenever it displays
b) generates on demand by a program or a request from browser
c) both is same every time whenever it displays and generates on demand by a program or a request from browser
d) is different always in a predefined order
Explanation: A dynamic web page provides different content every time the user opens it based on some events like new additions or time of the day. Languages such as JavaScript are used to respond to client-side events while languages such as PHP as used to respond to server-side events.
3. What is a web browser?
a) a program that can display a web page
b) a program used to view html documents
c) it enables user to access the resources of internet
d) all of the mentioned
Explanation: A web browser is an application program that is used to access the World Wide Web resources, applications and websites. Some examples of web browsers are Google Chrome, Internet Explorer and Safari.
4. Common gateway interface is used to _______
a) generate executable files from web content by web server
b) generate web pages
c) stream videos
d) download media files
Explanation: CGI is an interface through servers can run execute console-based executable files on a web server that generates dynamic web pages. A CGI script executes only when a request is made. The script then generates HTML.
5. URL stands for ________
a) unique reference label
b) uniform reference label
c) uniform resource locator
d) unique resource locator
Explanation: The Uniform Resource Locator is a locator for the resource to be located by HTTP on the World Wide Web. The URL is derived from the Uniform Resource Identifier.
6. A web cookie is a small piece of data that is _______
a) sent from a website and stored in user’s web browser while a user is browsing a website
b) sent from user and stored in the server while a user is browsing a website
c) sent from root server to all servers
d) sent from the root server to other root servers
Explanation: A web cookie is a small piece of data sent from a website and stored in user’s web browser while a user is browsing the website and is used to remember stateful information about the user’s operations on the website. This can help the website provide a better browsing experience to the user.
7. Which one of the following is not used to generate dynamic web pages?
a) PHP
b) ASP.NET
c) JSP
d) CSS
Explanation: CSS alone cannot be used to generate dynamic web pages as it does not provide many event handling functions. It can be used along with JavaScript to generate dynamic web pages which are visually compelling.
8. An alternative to JavaScript on windows platform is _______
a) VBScript
b) ASP.NET
c) JSP
d) PHP
Explanation: VBScript is a general-purpose, lightweight and active scripting language which can be used on Microsoft Visual Basic. It was first released in 1996.
9. What is document object model (DOM)?
a) convention for representing and interacting with objects in html documents
b) application programming interface
c) hierarchy of objects in ASP.NET
d) scripting language
Explanation: DOM is a hierarchical model i.e. a tree used to represent an HTML or XML document. Every node of the tree an object that represents a part of the document.
10. AJAX stands for _______
a) asynchronous javascript and xml
b) advanced JSP and xml
c) asynchronous JSP and xml
d) advanced javascript and xml
Explanation: AJAX is a group of technologies that works on the client-side to create asynchronous web applications. It is used to modify only a part of a webpage and not the whole webpage whenever some event occurs.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “ICMP”.
1. Internet Control Message Protocol (ICMP) has been designed to compensate _________
a) Error-reporting
b) Error-correction
c) Host and management queries
d) All of the mentioned
Explanation: IP by itself does not provide the features of error reporting or error correction. So, to address these issues a network layer protocol called Internet Control Message Protocol is used. ICMP operates over the IP packet to provide error reporting functionality.
2. Header size of the ICMP message is _________
a) 8-bytes
b) 8-bits
c) 16-bytes
d) 16-bits
Explanation: An ICMP message has an 8-byte header and a variable size data section. Out of the 8 bytes, the first 4 bytes are of a fixed format having the type, code and checksum fields and the next 4 bytes depend upon the type of the message.
3. During error reporting, ICMP always reports error messages to ________
a) Destination
b) Source
c) Next router
d) Previous router
Explanation: ICMP notifies the source about the error when an error is detected because the datagram knows information about source and destination IP address. The source can then retransmit the data again or try to correct those errors.
4. Which of these is not a type of error-reporting message?
a) Destination unreachable
b) Source quench
c) Router error
d) Time exceeded
Explanation: Router error is not a type of error-reporting message in ICMP. The type of error reporting message is specified in the ICMP header. Destination unreachable is type 3 error message, source quench is type 4, and time exceeded is type 11 error message.
5. ICMP error message will not be generated for a datagram having a special address such as _______
a) 127.0.0.0
b) 12.1.2
c) 11.1
d) 127
Explanation: 127.0.0.0 is a special address known as the loopback address which is used for testing purpose of a machine without actually communicating with a network. Thus no error reporting message will be generated for such special addresses.
6. When a router cannot route a datagram or host cannot deliver a
datagram, the datagram is discarded and the router or the host sends a
____________ message back to the source host that initiated the
datagram.
a) Destination unreachable
b) Source quench
c) Router error
d) Time exceeded
Explanation: Router sends destination unreachable message if the destination is not found. Destination unreachable is type 3 error reporting message. It is invoked when the router can’t find a path to the intended destination to forward the packet through.
7. The source-quench message in ICMP was designed to add a kind of ____________ to the IP.
a) error control
b) flow control
c) router control
d) switch control
Explanation: Firstly, it informs the source that the datagram has been discarded. Secondly, it warns the source that there is congestion in the network. It’s type 4 error reporting message after which the source is expected to reduce the flow of packets.
8. In case of time exceeded error, when the datagram visits a router, the value of time to live field is _________
a) Remains constant
b) Decremented by 2
c) Incremented by 1
d) Decremented by 1
Explanation: This field will be decremented by 1 at every router, and will be zero by the time it reaches source. This error reporting message is type 11 and is used to prevent the router from travelling forever in case some unknown path anomaly occurs.
9. Two machines can use the timestamp request and timestamp replay
messages to determine the ___________ needed for an IP datagram to
travel between them.
a) Half-trip time
b) Round-trip time
c) Travel time for the next router
d) Time to reach the destination/source
Explanation: The round-trip time refers to the total time taken combining the time taken for a packet sent from a source to reach a destination and the time taken the acknowledgement sent by the destination to reach the source. The Router sends destination unreachable message if the destination is not found.
10. During debugging, we can use the ____________ program to find if a host is alive and responding.
a) traceroute
b) shell
c) ping
d) java
Explanation: Ping program is used to find if a host is alive and responding. It is to be entered into a command line with the syntax “ping (IP address)” to be executed. Traceroute is a program used to find the shortest route to the destination IP.
11. In windows ____________ can be used to trace the route of the packet from the source to the destination.
a) traceroute
b) tracert
c) ping
d) locater
Explanation: Tracert is used in case of windows, whereas Traceroute in UNIX. Tracert is a program used to find the shortest route to the destination IP. The Router sends destination unreachable message if a path to the destination IP is not found.
Explanation: The sender side adds the bits of the fragmented packet to find a sum. Checksum is the compliment of the sum (exchange 0’s and 1’s). The receiver then has to verify the checksum by adding the bits of the received packet to ensure that the packet is error-free.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “IP Routing”.
1. Which type of Ethernet framing is used for TCP/IP and DEC net?
a) Ethernet 802.3
b) Ethernet 802.2
c) Ethernet II
d) Ethernet SNAP
Explanation: The Ethernet 802.3 framing is used for NetWare versions 2 to 3.11, and the Ethernet 802.2 framing is used for NetWare versions 3.12 and later plus OSI routing, Ethernet II is used with TCP/IP and DEC net, and Ethernet SNAP is used with TCP/IP and AppleTalk. The type field in Ethernet 802.2 frame is replaced by a length field in Ethernet 802.3.
2. Consider a situation in which you are a system administrator on a
NetWare network, you are running NetWare 4.11 and you cannot communicate
with your router. What is the likely problem?
a) NetWare 4.11 defaults to 802.2 encapsulation
b) NetWare 4.11 defaults to 802.3 encapsulation
c) Cisco routers only work with NetWare 3.11
d) NetWare 3.11 defaults to 802.2 encapsulation
Explanation: The default encapsulation on Cisco routers is Novell Ethernet_802.3 and NetWare 3.12and later defaults to 802.2 encapsulation, 3.11 and earlier defaults to 802.3.
3. NetWare IPX addressing uses a network number and a node number. Which statement is not true?
a) The network address is administratively assigned and can be up to 16 hexadecimal digits long
b) The node address is always administratively assigned
c) The node address is usually the MAC address
d) If the MAC address is used as the node address, then IPX eliminates the use of ARP
Explanation: The network address can be up to 16 hexadecimal digits in length. The node number is 12 hexadecimal digits. The node address is usually the MAC address. An example IPX address is 4a1d.0000.0c56.de33. The network part is 4a1d. The node part is 0000.0c56.de33. The network number is assigned by the system administrator of the Novell network and the MAC address/node address is not assigned by the administrator.
4. Which NetWare protocol works on layer 3–network layer—of the OSI model?
a) IPX
b) NCP
c) SPX
d) NetBIOS
Explanation: IPX (Internetwork Packet Exchange) is the NetWare network layer 3 protocol used for transferring information on LANs that use Novell’s NetWare.
5. Which NetWare protocol provides link-state routing?
a) NLSP
b) RIP
c) SAP
d) NCP
Explanation: NetWare Link Services Protocol (NLSP) provides link-state routing. SAP (Service Advertisement Protocol) advertises network services. NCP (NetWare Core Protocol) provides client-to-server connections and applications. RIP is a distance vector routing protocol. NLSP was developed by Novell to replace RIP routing protocols.
6. As a system administrator, you want to debug IGRP but are worried
that the “debug IP IGRP transaction” command will flood the console.
What is the command that you should use?
a) Debug IP IGRP event
b) Debug IP IGRP-events
c) Debug IP IGRP summary
d) Debug IP IGRP events
Explanation: The “debug IP IGRP events” is used to display a short summary of IGRP routing information. You can append an IP address onto either console’s command-line to see only the IGRP updates from a neighbor. The command will only give a short summary and hence won’t flood the command line.
7. What does the following series of commands “Router IGRP 71 network” accomplish?
10.0.0.0 router IGRP 109 network 172.68.7.0
a) It isolates networks 10.0.0.0 and 172.68.7.0
b) It loads IGRP for networks 109 and 71
c) It disables RIP
d) It disables all routing protocols
Explanation: It isolates network 10.0.0.0 and 172.68.7.0 and associates autonomous systems 109 and71 with IGRP. IGRP does not disable RIP, both can be used at the same time.
8. The “IPX delay number” command will allow an administrator to change the default settings. What are the default settings?
a) For LAN interfaces, one tick; for WAN interfaces, six ticks
b) For LAN interfaces, six ticks; for WAN interfaces, one tick
c) For LAN interfaces, zero ticks; for WAN interfaces, five ticks
d) For LAN interfaces, five ticks; for WAN interfaces, zero Ticks
Explanation: Tick is basically the update rate of clients in the network. The IPX delay number will give the ticks at a certain time. The default ticks are–for LAN interfaces, one tick, and for WAN interfaces, six ticks.
9. As a system administrator, you need to set up one Ethernet
interface on the Cisco router to allow for both sap and Novell-ether
encapsulations. Which set of commands will accomplish this?
a) Interface Ethernet 0.1 IPX encapsulation Novell-ether IPX network 9e interface
Ethernet 0.2 IPX network 6c
b) Interface Ethernet 0 IPX encapsulation Novell-ether IPX network 9e interface
Ethernet 0 IPX encapsulation sap IPX network 6c
c) Interface Ethernet 0.1 IPX encapsulation Novell-ether interface Ethernet 0.2 IPX
encapsulation sap
d) Interface Ethernet 0.1ipx encapsulation Novell-ether IPX network 9e interface
Ethernet 0.2 IPX encapsulation sap IPX network 6c
Explanation: The following commands setup the sub interfaces to allow for two types of encapsulation:interface Ethernet 0.1 IPX encapsulation Novell-ether IPX network 9e interface Ethernet0.2 IPX encapsulation sap IPX network 6c.
10. What does the “IPX maximum-paths 2” command accomplish?
a) It enables load sharing on 2 paths if the paths are equal metric paths
b) It sets up routing to go to network 2
c) It is the default for Cisco IPX load sharing
d) It enables load sharing on 2 paths if the paths are unequal metric paths
Explanation: It enables load sharing on 2 paths if the paths are equal metric paths. The default is 1 path and the maximum is 512 paths. The value must always be greater than 1 and must be a natural number.
Explanation: To assign multiple network numbers, you usually use sub interfaces. A sample configuration follows: IPXEthernet 0.1 IPX encapsulation novell-ether ipx network 9e interface ethernet 0.2 ipx encapsulation sap ipx network 6c
12. By default, Cisco routers forward GNS SAPs to remote networks.
a) False
b) True
Explanation: GNS is Novell’s protocol to Get Nearest Server. If there is a server on the local network,that server will respond. If there isn’t, the Cisco router has to be configured to forward theGNS SAP.
13. To prevent Service Advertisements (SAPs) from flooding a network,
Cisco routers do not forward them. How are services advertised to other
networks?
a) Each router builds its own SAP table and forwards that every 60 seconds
b) Each router assigns a service number and broadcasts that
c) SAPs aren’t necessary with Cisco routers
d) Cisco routers filter out all SAPs
Explanation: Cisco routers build SAP tables and forward the table every 60 seconds. All SAPs can’t befiltered even with 4.x since NDS and time synchronization uses SAPs.
14. Novell’s implementation of RIP updates routing tables every _________ seconds.
a) 60
b) 90
c) 10
d) 30
Explanation: Novell’s RIP updates routing tables every 60 seconds, Apple’s RTMP is every 10 seconds, routers ARP every 60 seconds, IGRP signal every 90 seconds, and Banyan VINES signals every 90 seconds.
15. In Novell’s use of RIP, there are two metrics used to make routing decisions. Select the correct metrics.
a) Ticks & Hops
b) Hops & Loops
c) Loops & Counts
d) Counts & Ticks
Explanation: It first uses ticks (which is about 1/18 sec.); if there is a tie, it uses hops; if hops are equal, then it uses an administratively assigned tiebreaker.
This set of Computer Networks Assessment Questions and Answers focuses on “Socket Programming”.
1. Which methods are commonly used in Server Socket class?
a) Public Output Stream get Output Stream ()
b) Public Socket accept ()
c) Public synchronized void close ()
d) Public void connect ()
Explanation: The Public socket accept () method is used by the ServerSocket class to accept the connection request of exactly one client at a time. The client requests by initializing the socket object with the servers IP address.
2. Which constructor of Datagram Socket class is used to create a datagram socket and binds it with the given Port Number?
a) Datagram Socket(int port)
b) Datagram Socket(int port, Int Address address)
c) Datagram Socket()
d) Datagram Socket(int address)
Explanation: Datagram Socket (int port, Int Address address) is used to create a datagram socket. A datagram socket is created for connection-less communication between the server and the client. There is no accept() method in this class.
3. The client in socket programming must know which information?
a) IP address of Server
b) Port number
c) Both IP address of Server & Port number
d) Only its own IP address
Explanation: The client in socket programming must know IP address of Server as it has to use that IP address in order to initialize the socket class constructor. That is how the client requests a connection to the server.
4. The URL Connection class can be used to read and write data to the specified resource that is referred by the URL.
a) True
b) False
Explanation: The URL Connection class can be used to read and write data to the specified resource referred by the URL. A connection to the URL is initialized by the OpenConnection() method of the class.
5. Datagram is basically just a piece of information but there is no guarantee of its content, arrival or arrival time.
a) True
b) False
Explanation: Datagram is basically some information travelling between the sender and the receiver, but there is no guarantee of its content, arrival or arrival time. A Datagram socket class object is created to make a datagram connection between the server and the client.
6. TCP, FTP, Telnet, SMTP, POP etc. are examples of ___________
a) Socket
b) IP Address
c) Protocol
d) MAC Address
Explanation: TCP, FTP, Telnet, SMTP, POP etc. are examples of Protocol. Out of them, TCP is a transport layer protocol and FTP, TELNET, SMTP and POP are application layer protocols.
7. What does the java.net.InetAddress class represent?
a) Socket
b) IP Address
c) Protocol
d) MAC Address
Explanation: The java.net.InetAddress class represents IP Address of a particular specified host. It can be used to resolve the host name from the IP address or the IP address from the host name.
8. The flush () method of Print Stream class flushes any un-cleared buffers in the memory.
a) True
b) False
Explanation: The flush () method of Print Stream class flushes any un cleared buffers in memory.
9. Which classes are used for connection-less socket programming?
a) Datagram Socket
b) Datagram Packet
c) Both Datagram Socket & Datagram Packet
d) Server Socket
Explanation: Datagram is basically some information travelling between the sender and the receiver, but there is no guarantee of its content, arrival or arrival time. Datagram Socket, Datagram Packet are used for connection-less socket programming, while Server Socket is used for connection-oriented socket programming.
10. In Inet Address class, which method returns the host name of the IP Address?
a) Public String get Hostname()
b) Public String getHostAddress()
c) Public static InetAddress get Localhost()
d) Public getByName()
Explanation: In Inet Address class public String getHostname() method returns the host name of the IP Address. The getHostAddress() method returns the IP address of the given host name.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “OSPF”.
1. Open Shortest Path First (OSPF) is also called as _____________
a) Link state protocol
b) Error-correction protocol
c) Routing information protocol
d) Border gateway protocol
Explanation: In OSPF, the link state of each path is checked, and then the shortest path is chosen among only the open state links. Each OSPF router monitors the cost of the link to each of its neighbors and then floods the link state information to other routers in the network.
2. The computation of the shortest path in OSPF is usually done by ____________
a) Bellman-ford algorithm
b) Routing information protocol
c) Dijkstra’s algorithm
d) Distance vector routing
Explanation: Shortest path in OSPF is usually computed by Dijkstra’s algorithm. It was proposed by Edsger W. Dijkstra in the year 1956. It is a greedy method algorithm and hence may not guarantee the shortest path every time, but is really fast.
3. Which of the following is false with respect to the features of OSPF?
a) Support for fixed-length subnetting by including the subnet mask in the routing message
b) More flexible link cost than can range from 1 to 65535
c) Use of designated router
d) Distribution of traffic over multiple paths that have equal cost to the destination
Explanation: OSPF provides support for variable-length sunbathing by including the subnet mask in the routing message. For fixed length subnets, there is no requirement for including the subnet mask in the routing message as there is just one subnet mask for all the subnets.
4. In OSPF, which protocol is used to discover neighbour routers automatically?
a) Link state protocol
b) Error-correction protocol
c) Routing information protocol
d) Hello protocol
Explanation: Hello protocol is used to discover neighboring routers automatically. It makes sure that the communication between neighbors is bidirectional. It’s similar to the real world moral construct of saying “Hello” to initialize the communication.
5. Which of the following is not a type of OSPF packet?
a) Hello
b) Link-state request
c) Link-state response
d) Link-state ACK
Explanation: The five types of OSPF packets are: Hello, Database description, Link-state request, Link-state update, and Link-state ACK. There is no Link-state response packet; the neighbor router sends a Link-state update packet as a response to the Link-state request packet if there is an update in the routing table.
6. What is the correct order of the operations of OSPF?
i – Hello packets
ii – Propagation of link-state information and building of routing tables
iii – Establishing adjacencies and synchronization of database
a) i-ii-iii
b) i-iii-ii
c) iii-ii-i
d) ii-i-iii
Explanation: OSPF first implements a hello protocol. Then it later on tries to establish synchronisation with database. Later on building of routing tables is done.
7. In OSPF header, which field is used to detect errors in the packet?
a) Type
b) Area ID
c) Authentication type
d) Checksum
Explanation: Checksum field is used to detect errors. It makes sure that the data portions that are being sent are all in integrity. It can detect duplicated bits. Once an error is detected, the sender has to re-transmit the data as it won’t receive an acknowledgement.
8. In OSPF database descriptor packet, if there are more database
descriptor packets in the flow, ‘M’ field is set to ____________
a) 1
b) 0
c) more
d) -1
Explanation: The “M” bit is the more bit, which indicates that there are more packets to be received in the descriptor packet flow whenever it is set to 1. There is also an “I” bit which indicates if the packet is first in the flow.
9. In OSPF database descriptor packet, which field is used to indicate that the router is master?
a) M
b) MS
c) I
d) Options
Explanation: The MS bit is used to indicate if the origin of the packet is a master or a slave. If it is set to 1, the source of the packet is a master, and if it is set to 0, the source of the packet is a slave.
10. In OSPF database descriptor packet, which field is used to detect a missing packet?
a) LSA header
b) MS
c) Database descriptor sequence number
d) Options
Explanation: Sequence number field is used to detect a missing packet. The packets are to be received in order of the sequence number, so if the receiver detects that there is a sequence number skipped or missing in the order, it stops processing the further received packets and informs the sender to retransmit the packets in sequence.
This set of Computer Networks Question Bank focuses on “Network Management”.
1. Complex networks today are made up of hundreds and sometimes thousands of _________
a) Documents
b) Components
c) Servers
d) Entities
Explanation: Complex networks today are made up of hundreds and sometimes thousands of components. For effective functioning of these thousands of components, good network management is essential.
2. Performance management is closely related to _________
a) Proactive Fault Management
b) Fault management
c) Reactive Fault Management
d) Preventive Fault Management
Explanation: Fault management is really closely related to performance management. It is important to ensure that the network handles faults as effectively as it handles it’s normal functioning to achieve better performance management.
3. Configuration management can be divided into two subsystems: reconfiguration and __________
a) Documentation
b) Information
c) Servers
d) Entity
Explanation: The documentation subsystem of configuration management handles the log making and reporting functions of the configuration management. It also reports the errors in the network caused by the configuration’s failure.
4. In Network Management System, the term that is responsible for
controlling access to network based on predefined policy is called
___________
a) Fault Management
b) Secured Management
c) Active Management
d) Security Management
Explanation: In Network Management System, the term that is responsible for controlling access to the network based on predefined policy is called security management. The security management ensures authentication, confidentiality and integrity in the network.
5. Control of users’ access to network resources through charges is the main responsibility of ______________
a) Reactive Fault Management
b) Reconfigured Fault Management
c) Accounting Management
d) Security Management
Explanation: Control of users’ access to network resources through charges is the main responsibility of accounting management. The accounting management creates a log of the users activity on the network too and goes hand-in-hand with the configurations management.
6. The physical connection between an end point and a switch or between two switches is __________
a) Transmission path
b) Virtual path
c) Virtual circuit
d) Transmission circuit
Explanation: The physical connection between an end point and a switch or between two switches is transmission path. The transmission path is the physical roadway that the packet needs to propagate in order to travel through the network.
7. Which of the following networks supports pipelining effect?
a) Circuit-switched networks
b) Message-switched networks
c) Packet-switched networks
d) Stream-switched networks
Explanation: Packet switched network is most preferred for pipelining process. Pipelining exponentially reduces the time taken to transmit a large number of packets in the network.
8. In Network Management System, maps track each piece of hardware and its connection to the _________
a) IP Server
b) Domain
c) Network
d) Data
Explanation: Network is the main entity connecting different components in a place. A network map is made to track each component and its connection to the network to ensure better network management.
9. MIB is a collection of groups of objects that can be managed by __________
a) SMTP
b) UDP
c) SNMP
d) TCP/IP
Explanation: MIB stands for Management Information Base. Simple network management controls the group of objects in management information base. It is usually used with SNMP (Simple Network Management Protocol).
10. A network management system can be divided into ___________
a) three categories
b) five broad categories
c) seven broad categories
d) ten broad categories
Explanation: The five broad categories of network management are
• Fault Management
• Configuration Management
• Accounting (Administration)
• Performance Management
• Security Management.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “Wireless LAN”.
1. What is the access point (AP) in a wireless LAN?
a) device that allows wireless devices to connect to a wired network
b) wireless devices itself
c) both device that allows wireless devices to connect to a wired network and wireless devices itself
d) all the nodes in the network
Explanation: Access point in a wireless network is any device that will allow the wireless devices to a wired network. A router is the best example of an Access Point.
2. In wireless ad-hoc network _________
a) access point is not required
b) access point is must
c) nodes are not required
d) all nodes are access points
Explanation: An ad-hoc wireless network is a decentralized kind of a wireless network. An access point is usually a central device and it would go against the rules of the ad-hoc network to use one. Hence it is not required.
3. Which multiple access technique is used by IEEE 802.11 standard for wireless LAN?
a) CDMA
b) CSMA/CA
c) ALOHA
d) CSMA/CD
Explanation: CSMA/CA stands for Carrier-sense multiple access/collision avoidance. It is a multiple access protocol used by IEEE 802.11 standard for wireless LAN. It’s based on the principle of collision avoidance by using different algorithms to avoid collisions between channels.
4. In wireless distribution system __________
a) multiple access point are inter-connected with each other
b) there is no access point
c) only one access point exists
d) access points are not required
Explanation: A Wireless Distribution System allows the connection of multiple access points together. It is used to expand a wireless network to a larger network.
5. A wireless network interface controller can work in _______
a) infrastructure mode
b) ad-hoc mode
c) both infrastructure mode and ad-hoc mode
d) WDS mode
Explanation: A wireless network interface controller works on the physical layer and the data link layer of the OSI model. Infrastructure mode WNIC needs access point but in ad-hoc mode access point is not required.
6. In wireless network an extended service set is a set of ________
a) connected basic service sets
b) all stations
c) all access points
d) connected access points
Explanation: The extended service set is a part of the IEEE 802.11 WLAN architecture and is used to expand the range of the basic service set by allowing connection of multiple basic service sets.
7. Mostly ________ is used in wireless LAN.
a) time division multiplexing
b) orthogonal frequency division multiplexing
c) space division multiplexing
d) channel division multiplexing
Explanation: In orthogonal frequency division multiplexing, digital data is encoded on multiple carrier frequencies. It is also used in digital television and audio broadcasting in addition to Wireless LANs.
8. Which one of the following event is not possible in wireless LAN?
a) collision detection
b) acknowledgement of data frames
c) multi-mode data transmission
d) connection to wired networks
Explanation: Collision detection is not possible in wireless LAN with no extensions. Collision detection techniques for multiple access like CSMA/CD are used to detect collisions in Wireless LANs.
9. What is Wired Equivalent Privacy (WEP)?
a) security algorithm for ethernet
b) security algorithm for wireless networks
c) security algorithm for usb communication
d) security algorithm for emails
Explanation: WEP is a security algorithm for wireless network which intended to provide data confidentiality comparable to that of traditional wired networks. It was introduced in 1997.
10. What is WPA?
a) wi-fi protected access
b) wired protected access
c) wired process access
d) wi-fi process access
Explanation: WPA or WiFi Protected Access is a security protocol used to provide users and firms with strong data security and protection for their wireless networks (WiFi) to give them confidence that only authorized users can access their network.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “SONET”.
1. SONET stands for ___________
a) synchronous optical network
b) synchronous operational network
c) stream optical network
d) shell operational network
Explanation: SONET stands for synchronous optical network. Frame relay uses SONET to physically transmit data frames over a Frame Relay network as SONET is cheaper and provides better network reliability than other carriers.
2. In SONET, STS-1 level of electrical signalling has the data rate of _________
a) 51.84 Mbps
b) 155.52 Mbps
c) 2488.320 Mbps
d) 622.080 Mbps
Explanation: STS-1 level provides the data rate of 51.84 Mbps, STS-3 provides a data rate of 155.52 Mbps, STS-12 provides a data rate of 622.080 Mbps and STS-48 provides a data rate of 2488.320 Mbps.
3. The path layer of SONET is responsible for the movement of a signal _________
a) from its optical source to its optical destination
b) across a physical line
c) across a physical section
d) back to its optical source
Explanation: The path layer in SONET is responsible for finding the path of the signal across the physical line to reach the optical destination. It is ideally expected to find the shortest and the most reliable path to the destination.
4. The photonic layer of the SONET is similar to the __________ of OSI model.
a) network layer
b) data link layer
c) physical layer
d) transport layer
Explanation: The photonic layer in SONET is like the physical layer of the OSI model. It is the lowest layer among the four layers of SONET namely the photonic, the section, the line, and the path layers.
5. In SONET, each synchronous transfer signal STS-n is composed of __________
a) 2000 frames
b) 4000 frames
c) 8000 frames
d) 16000 frames
Explanation: SONET defines the electrical signal as STS-N (Synchronous Transport Signal Level-N) and the optical signal as OC-N (Optical Carrier Level-N). The building block of SONET is the STS-1/OC-1 signal, which is based on an 8-kHz frame rate and operates at 51.84 Mbps.
6. Which one of the following is not true about SONET?
a) frames of lower rate can be synchronously time-division multiplexed into a higher-rate frame
b) multiplexing is synchronous TDM
c) all clocks in the network are locked to a master clock
d) STS-1 provides the data rate of 622.080Mbps
Explanation: In SONET, STS-N stands for Synchronous Transport Signal Level-N. STS-1 level provides the data rate of 51.84 Mbps, and STS-12 provides a data rate of 622.080 Mbps.
7. A linear SONET network can be ________
a) point-to-point
b) multi-point
c) both point-to-point and multi-point
d) single point
Explanation: Synchronous Optical Network (SONET) is basically an optical fiber point-to-point or ring network backbone that provides a way to accommodate additional capacity as the needs of the organization increase to multipoint networks.
8. Automatic protection switching in linear network is defined at the _______
a) line layer
b) section layer
c) photonic layer
d) path layer
Explanation: The Line layer in SONET operates like the data link layer in the OSI model and it is responsible for the movement of signal across a physical line. The Synchronous Transport Signal Mux/Demux and Add/Drop Mux provide the Line layer functions.
9. A unidirectional path switching ring is a network with __________
a) one ring
b) two rings
c) three rings
d) four rings
Explanation: One ring is used as the working ring and other as the protection ring in which each node is connected to its respective adjacent nodes by two fibers, one to transmit, and one to receive.
10. What is SDH?
a) sdh is similar standard to SONET developed by ITU-T
b) synchronous digital hierarchy
c) sdh stands for synchronous digital hierarchy and is a similar standard to SONET developed by ITU-T
d) none of the mentioned
Explanation: SDH is a standard that allows low bit rates to be combined into high-rate data streams and as it is synchronous, each individual bit stream can be embedded into and extracted from high-rate data streams easily.
This set of Computer Networks Questions and Answers for Entrance exams focuses on “Intrusion Detection Systems”.
1. Which of the following is an advantage of anomaly detection?
a) Rules are easy to define
b) Custom protocols can be easily analyzed
c) The engine can scale as the rule set grows
d) Malicious activity that falls within normal usage patterns is detected
Explanation: Once a protocol has been built and a behavior defined, the engine can scale more quickly and easily than the signature-based model because a new signature does not have to be created for every attack and potential variant.
2. A false positive can be defined as ________
a) An alert that indicates nefarious activity on a system that, upon
further inspection, turns out to represent legitimate network traffic or
behavior
b) An alert that indicates nefarious activity on a system that is not running on the network
c) The lack of an alert for nefarious activity
d) Both An alert that indicates nefarious activity on a system that,
upon further inspection, turns out to represent legitimate network
traffic or behavior and An alert that indicates nefarious activity on a
system that is not running on the network
Explanation: A false positive is any alert that indicates nefarious activity on a system that, upon further inspection, turns out to represent legitimate network traffic or behavior.
3. One of the most obvious places to put an IDS sensor is near the
firewall. Where exactly in relation to the firewall is the most
productive placement?
a) Inside the firewall
b) Outside the firewall
c) Both inside and outside the firewall
d) Neither inside the firewall nor outside the firewall.
Explanation: There are legitimate political, budgetary and research reasons to want to see all the “attacks” against your connection, but given the care and feeding any IDS requires, do yourself a favor and keep your NIDS sensors on the inside of the firewall.
4. What is the purpose of a shadow honeypot?
a) To flag attacks against known vulnerabilities
b) To help reduce false positives in a signature-based IDS
c) To randomly check suspicious traffic identified by an anomaly detection system
d) To enhance the accuracy of a traditional honeypot
Explanation: “Shadow honeypots,” as researchers call them, share all the same characteristics of protected applications running on both the server and client side of a network and operate in conjunction with an ADS.
5. At which two traffic layers do most commercial IDSes generate signatures?
a) Application layer and Network layer
b) Network layer and Session Layer
c) Transport layer and Application layer
d) Transport layer and Network layer
Explanation: Most commercial IDSes generate signatures at the network and transport layers. These signatures are used to ensure that no malicious operation is contained in the traffic. Nemean generates signature at application and session layer.
6. IDS follows a two-step process consisting of a passive component
and an active component. Which of the following is part of the active
component?
a) Inspection of password files to detect inadvisable passwords
b) Mechanisms put in place to reenact known methods of attack and record system responses
c) Inspection of system to detect policy violations
d) Inspection of configuration files to detect inadvisable settings
Explanation: Secondary components of mechanism are set in place to reenact known methods of attack and to record system responses. In passive components, the system I designed just to record the system’s responses in case of an intrusion.
7. When discussing IDS/IPS, what is a signature?
a) An electronic signature used to authenticate the identity of a user on the network
b) Attack-definition file
c) It refers to “normal,” baseline network behavior
d) It is used to authorize the users on a network
Explanation: IDSes work in a manner similar to modern antivirus technology. They are constantly updated with attack-definition files (signatures) that describe each type of known malicious activity. Nemean is a popular signature generation method for conventional computer networks.
8. “Semantics-aware” signatures automatically generated by Nemean are based on traffic at which two layers?
a) Application layer and Transport layer
b) Network layer and Application layer
c) Session layer and Transport layer
d) Application layer and Session layer
Explanation: Nemean automatically generates “semantics-aware” signatures based on traffic at the session and application layers. These signatures are used to ensure that no malicious operation is contained in the traffic.
9. Which of the following is used to provide a baseline measure for comparison of IDSes?
a) Crossover error rate
b) False negative rate
c) False positive rate
d) Bit error rate
Explanation: As the sensitivity of systems may cause the false positive/negative rates to vary, it’s critical to have some common measure that may be applied across the board.
10. Which of the following is true of signature-based IDSes?
a) They alert administrators to deviations from “normal” traffic behavior
b) They identify previously unknown attacks
c) The technology is mature and reliable enough to use on production networks
d) They scan network traffic or packets to identify matches with attack-definition files
Explanation: They are constantly updated with attack-definition files (signatures) that describe each type of known malicious activity. They then scan network traffic for packets that match the signatures, and then raise alerts to security administrators.
This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “EIGRP”.
1. EIGRP is a routing protocol design by Cisco.
a) True
b) False
Explanation: EIGRP stands for Enhanced Interior Gateway Routing Protocol is a routing protocol designed by Cisco. It is available only on Cisco routers.
2. EIGRP metric is ________
a) K-values
b) Bandwidth only
c) Hop Count
d) Delay only
Explanation: EIGRP metric is K-values which are integers from 0 to 128. They are used to calculate the overall EIGRP cost with bandwidth and delay metrics.
3. EIGRP can support ____________
a) VLSM/subnetting
b) Auto summary
c) Unequal cast load balancing
d) All of the mentioned
Explanation: EIGRP supports variable and fixed length subnetting, Auto summary, and Unequal cast load balancing to provide efficient routing functionality on Cisco routers.
4. EIGRP sends a hello message after every ___________ seconds.
a) 5 seconds (LAN), 60 seconds (WAN)
b) 5 seconds (LAN), 5 seconds (WAN)
c) 15s
d) 180s
Explanation: EIGRP routers broadcast the hello packets frequently to familiarize with the neighbors. EIGRP routers send the hello message after every 5 seconds on LAN, and every 60 seconds on WAN.
5. Administrative distance for internal EIGRP is ______
a) 90
b) 170
c) 110
d) 91
Explanation: Routers use the metric of administrative distance to select the best path when there are different routes to the same destination from two different routing protocols as it is a measure of reliability of routing protocols. Administrative distance for internal EIGRP is 90.
6. The EIGRP metric values include:
a) Delay
b) Bandwidth
c) MTU
d) All of the mentioned
Explanation: The EIGRP metric values are Delay, Bandwidth, and MTU. MTU stands for Maximum Transmission Unit. They are combined together to give the overall EIGRP cost in K-values.
7. For default gateway, which of following commands will you use on a Cisco router?
a) IP default network
b) IP default gateway
c) IP default route
d) Default network
Explanation: IP default network command is used to find the default gateway in Cisco router. If the router finds routes to the node, it considers the routes to that node for installation as the gateway to it.
8. Administrative distance for external EIGRP route is _______
a) 90
b) 170
c) 110
d) 100
Explanation: Routers use the metric of administrative distance to select the best path when there are different routes to the same destination from two different routing protocols as it is a measure of reliability of routing protocols. Administrative distance for external EIGRP is 170.
9. EIGRP uses the ____________ algorithm for finding shortest path.
a) SPF
b) DUAL
c) Linkstat
d) Djikstra’s
Explanation: EIGRP uses the DUAL algorithm for finding shortest path. DUAL stands for diffusing update algorithm and it is used to prevent routing loops by recalculating routes globally.
10. In EIGRP best path is known as the successor, where as backup path is known as __________
a) Feasible successor
b) Back-up route
c) Default route
d) There is no backup route in EIGRP
Explanation: Feasible successor is the backup path. The backup path is used alternatively used whenever the best path fails. It is not used primarily because it is comparatively expensive than the best path.
