Computer Networks Gate Questions

Here, We will see Computer Networks GATE Questions from previous year’s papers and the syllabus of Computer Networks for GATE Exam.

1. Computer Networks in Gate CSE Exam

The Computer Networks section in the GATE Computer Science and Information Technology (CS/IT) exam evaluates conceptual clarity and problem-solving skills through topics like protocol layers, routing algorithms, and application-layer protocols. Below is a concise overview of the syllabus and question patterns to streamline your preparation.

2. Computer Networks Syllabus

The syllabus for Computer Networks in GATE CSE includes:

1. Layered Architectures: OSI and TCP/IP models, packet/circuit switching.
2. Data Link Layer: Framing, error detection (CRC, checksum), MAC protocols (Ethernet, CSMA/CD), and bridging.
3. Network Layer: IP addressing (IPv4, CIDR), routing protocols (shortest path, distance vector), fragmentation, NAT, and support protocols (ARP, DHCP).
4. Transport Layer: TCP/UDP, flow control (sliding window), congestion control (AIMD, leaky bucket).
5. Application Layer: DNS, HTTP, SMTP, FTP, and email systems.

Computer Networks Gate Questions

Q. Bluetooth is an example of:

1. Personal area network
2. Virtual private network
3. Local area network
4. None of the above

Q. The process of converting the analog sample into discrete form is called

1. Modulation
2. Multiplexing
3. Quantization
4. Sampling

Q. In networking terminology UTP means

1. Unshielded Twisted pair
2. Ubiquitious Teflon port
3. Uniformly Terminating port
4. Unshielded T-connector port

Q. Communication between a computer and a keyboard involves _ transmission

1. Simplex
2. Half-Duplex
3. Automatic
4. Full-Duplex

Q. What is WPA?

1. wi-fi protected access
2. wired protected access
3. wired process access
4. wi-fi process access

Q. The first Network:

1. ARPANET.
2. NFSNET.
3. CNNET.
4. ASAPNET.

Q. Which of this is not a network edge device?

1. PC
2. Server
3. Smartphone
4. Switch

Q. Three or more devices share a link in _______ connection

1. Unipoint
2. Polarpoint
3. Point to point
4. Multipoint

Q. If the channel is band limited to 6kHz and signal to noise ratio is 16, what would be the capacity of channel?

1. 16.15 kbps
2. 23.24 kbps
3. 40.12 kbps
4. 24.74 kbps

Q. TCP/IP model does not have _________ layer but OSI model have this layer.

1. session layer
2. transport layer
3. application layer
4. network layer

Q. If the CRC has Polynomial of degree n, then what is the probability of detecting errors greater then n?

1. 1/2^n-1
2. 1/2ⁿ⁺¹
3. 1/2ⁿ
4. 1/2ⁿ⁺²

Q. Start and stop bits are used in serial communication for

1. error detection
2. error correction
3. synchronization
4. slowing down the communication

Q. Two alternative packages A and B are available for processing a database having 10^k records. Package A requires 0.0001n² time units and package B requires 10nlog₁₀n time units to process n records. What is the smallest value of k for which package B will be preferred over A?

1. 12
2. 10
3. 6
4. 5

Q. Repeaters function in

1. Physical layer
2. Data link layer
3. Network layer
4. Both (A) and (B)

Q. What are the primary characteristics that distinguish a cell from a packet?

1. cells are generally smaller that packets
2. cells do not incorporate physical address
3. all cells have the same fixed length
4. packet cannot be switched

Q. What is the access point(AP) in a wireless LAN?

1. device that allows wireless devices to connect to a wired network
2. wireless devices itself
3. both device that allows wireless devices to connect to a wired network and wireless devices itself
4. all the nodes in the network

Q. Which multiple access technique is used by IEEE 802.11 standard for wireless LAN?

1. CDMA
2. CSMA/CA
3. ALOHA
4. CSMA/CD

Q. For a hamming code of parity bit m=5, what is the total bits and data bits?

1. (255,247)
2. (127,119)
3. (31,26)
4. (0,8)

Q. The maximum data rate of a channel of 3000-Hz bandwidth and SNR of 30db is

1. 60000
2. 15000
3. 30000
4. 3000

Q. Application layer protocol defines:

1. types of messages exchanged
2. rules for when and how processes send and respond to messages
3. message format, syntax and semantics
4. all of the above

Q. Bit stuffing refers to

1. Inserting a ‘0’ in user data stream to differentiate it with a flag
2. Inserting a ‘0’ in flag stream to avoid ambiguity
3. Appending a nibble to the flag sequence
4. Appending a nibble to the user data stream

Q. The DoS attack, in which the attacker establishes a large number of half-open or fully open TCP connections at the target host is ________ .

1. Vulnerability attack
2. Bandwidth flooding
3. Connection flooding
4. UDP flooding

Q. Closed-Loop control mechanism try to :

1. Remove congestion after it occurs
2. Remove congestion after sometime
3. Prevent congestion before it occurs
4. Prevent congestion before sending packets

Q. Which is the layer that converts packets to Frames and Frames to packets in the OSI model?

1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer

Q. Which of the following system calls results in the sending of SYN packets?

1. Socket
2. Bind
3. Listen
4. Connect

Q. If all transactions obey the ______ then all possible interleaved schedules (non-serial schedules) are serializable.

1. Lock based protocol
2. Two phase Locking protocol
3. Read-write lock based protocol
4. Time stamp based protocol

Q. When we use slow-start algorithm, the size of the congestion window increases _ until it reaches a threshol1.

1. Additively
2. Multiplicatively
3. Exponentially
4. None of the options

Q. Why does congestion occur?

1. Because the routers and switches have tables
2. Because the routers and switches have queues
3. Because the routers and switches have cross-points
4. None of the options

Q. In CRC calculation if divisor is 1011, and dataword is 1001 what will be the CRC?

1. 111
2. 101
3. 110
4. 100

Q. In CSMA/CD after detecting the collision, station immediately stops transmission by sending the _______ .

1. Stop pattern
2. Preamble pattern
3. Jam signal
4. Block signal

Q. Which address is used to identify a process on a host by the transport layer

1. physical address
2. logical address
3. port address
4. specific address

Q. Which multiple access technique is used by IEEE 802.11 standard for wireless LAN?

1. CDMA
2. CSMA/CA
3. ALOHA
4. None of the options

Q. The ___________ is the physical path over which a message travels.

1. Path
2. Protocol
3. Route
4. Medium

Q. A digital signature is required:

1. for non-repudiation of communication by a sender
2. for all e-mail sending
3. for all DHCP server
4. for FTP transactions

Q. Which NetWare protocol works on layer 3-network layer of the OSI model ?

1. IPX
2. NCP
3. SPX
4. NetBIOS

Q. Who developed standards for the OSI reference model?

1. ANSI– American National Standards Institute
2. ISO– International Standards Organization
3. IEEE– Institute of Electrical and Electronics Engineering
4. ACM– Association for Computing Machinery

Q. Each layer of the OSI model receives services or data from a _______ layer.

1. below layer
2. above layer
3. both 1 and 2
4. None of the above

Q. If the original size of data is 40, then after adding error detection redundancy bit the size of data length is

1. 26
2. 36
3. 46
4. 56

Q. A wireless network interface controller can work in __________ .

1. infrastructure mode
2. ad–hoc mode
3. both infrastructure mode and adhoc mode
4. WDS mode

Q. The demerits of the fragmentation are :

1. Complex routers
2. Open to DOS attack
3. No overlapping of fragments
4. (A) and (B) both

Q. The ___________ field in IPv4 datagram is not related to fragmentation.

1. Flag
2. Offset
3. TOS
4. Identifier

Q. To guarantee correction of upto 5 errors in all cases, the minimum Hamming distance in a block code must be ____________ .

1. 11
2. 6
3. 5
4. 2

Q. Which layer connects the network support layers and user support layers ?

1. transport layer
2. network layer
3. data link layer
4. session layer

Q. In ICMP, in case of time exceeded error, when the datagram visits a router, the value of time to live field is

1. Remains constant
2. Decremented by 2
3. Incremented by 1
4. Decremented by 1

Q. Which protocol finds the MAC address from IP address?

1. SMTP
2. ICMP
3. ARP
4. RARP

Q. The File Transfer Protocol is built on ________.

1. data centric architecture
2. service-oriented architecture
3. client server architecture
4. connection-oriented architecture

Q. In classless addressing, there are no classes but addresses are still granted in

1. Codes
2. Blocks
3. IPs
4. Sizes

Q. A subnet mask in class C can have __________ 1’s with the remaining bits 0’s.

1. 10
2. 24
3. 12
4. 7

Q. In IPv4 Addresses, classfull addressing is replaced with :

1. Classless Addressing
2. Classfull Addressing
3. Subnet Advertising
4. None of the options

Q. _____________ IP address can be used in WAN

1. 256.0.0.1
2. 172.16.0.10
3. 15.1.5.6
4. 127.256.0.1

Q. A packet switching network

1. is free.
2. can reduce the cost of using an information utility.
3. allows communications channel to be shared among more than one user.
4. both (B) and (C).

Q. Which of the following is a class B host address ?

1. 230.0.0.0
2. 130.4.5.6
3. 230.7.6.5
4. 30.4.5.6

Q. In an IPv4 datagram, the M bit is 0, the value of HLEN is 10, the value of total length is 400 and the fragment offset value is 300. The position of the datagram, the sequence numbers of the first and the last bytes of the payload, respectively are:

1. Last fragment, 2400 and 2789
2. First fragment, 2400 and 2759
3. Last fragment, 2400 and 2759
4. Middle fragment, 300 and 689

Q. The routing table of a router is shown below:

On which interfaces will the router forward packets addressed to destinations 128.75.43.16 and 192.12.17.10 respectively?

1. Eth1 and Eth2
2. Eth0 and Eth2
3. Eth0 and Eth3
4. Eth1 and Eth3

Q. Find out the maximum link speed at which a source can generate 1500-byte TCP payloads with packet lifetime of upto 120 msec before the 32-bit sequence numbers wrap around? Take into account TCP, IPv4 and Ethernet header overheads while doing all calculations.

1. 137 mbps
2. 256 mbps
3. 299 mbps
4. 512 mbps

Q. Host A sends a UDP datagram containing 8880 bytes of user data to host B over an Ethernet LAN. Ethernet frames may carry data up to 1500 bytes (i.e. MTU = 1500 bytes). Size of UDP header is 8 bytes and size of IP header is 20 bytes. There is no option field in IP header. How many total number of IP fragments will be transmitted and what will be the contents of offset field in the last fragment?

1. 6 and 925
2. 6 and 7400
3. 7 and 1110
4. 7 and 8880

Q. There is a need to create a network that has 5 subnets, each with at least 16 hosts. Which one is used as classful subnet mask ?

1. 255.255.255.192
2. 255.255.255.248
3. 255.255.255.240
4. 255.255.255.224

Q. An Ethernet destination address 07-01-12-03-04-05 is

1. Unicast address
2. Multicast address
3. Broadcast address
4. All of the options

Q. A device that allows two or more computers on different networks to communicate with each other is ____________ .

1. Hub
2. Bridge
3. Repeater
4. Gateway

Q. Which TCP/IP protocol is used for file transfer with minimal capability and minimal overhead?

1. RARP
2. FTP
3. TFTP
4. TELNET

Q. If the number of networks and number of hosts in class B are 2^m,(2ⁿ -2) respectively. Then the relation between m,n is

1. 3m=2n
2. 7m=8n
3. 8m=7n
4. 2m=3n

Q. Which of the following is not a transceiver function?

1. Transmission and receipt of data
2. Checking of line voltages
3. Addition and subtraction of headers
4. Collision detection

Q. In a network, If IP is the only packet being transmitted and there was no earlier transmission, which of the following delays could be zero?

1. Propagation delay
2. Queuing delay
3. Transmission delay
4. Processing delay

Q. The router table contains addresses belonging to _ protocol(s).

1. a single
2. two
3. multiple
4. none of the options

Q. A set of rules that governs data communication:

1. Rule
2. Medium
3. Link
4. Protocol

Q. Which NetWare protocol provides link-state routing ?

1. NLSP
2. RIP
3. SAP
4. NCP

Q. A message is made up entirely of characters from the set X={P,Q,R,S,T}. The table of probabilities for each of the characters is shown below:

If a message of 100 characters over X is encoded using Huffman coding, then the expected length of the encoded message in bits is ________.

1. 225
2. 226
3. 227
4. 228

Q. _______________ tells a firewall about how to reassemble a data stream that has been divided into packets.

1. The source routing feature
2. The number in the header’s identification field
3. The destination IP address
4. The header checksum field in the packet header

Q. A sender uses the Stop-and-Wait ARQ protocol for reliable transmission of frames. Frames are of size 1000 bytes and the transmission rate at the sender is 80 kbps (1 kbps = 1000 bits/second). Size of an acknowledgement is 100 bytes and the transmission rate at the receiver is 8 kbps. The one-way propagation delay is 100 milliseconds. Assuming no frame is lost, the sender throughput is __________ bytes/second.

1. 2500
2. 2000
3. 1500
4. 500

Q. You are working with a network that is 172.16.0.0 and would like to support 600 hosts per subnet. What subnet mask should you use?

1. 255.255.192.0
2. 255.255.224.0
3. 255.255.252.0
4. None of the options

Q. Given message M=1010001101. The CRC for this given message using the divisor polynomial x⁵+ x⁴ + x²+1 is __

1. 01011
2. 10101
3. 01110
4. 10110

Q. Which of the following is the efficient medium which can be used for higher bandwidth in broadband network?

1. Coaxial cable
2. Optical fiber
3. CAT-V
4. STP

Q. The ______ command will show you the translation table containing all the active NAT entries.

1. show ip nat translations
2. show ip nat tl
3. show ip nat states
4. none of the options

Q. Identify the true statement from the given statements.
1. HTTP may use different TCP connection for different objects of a webpage if non-persistent connections are used
2. FTP uses two TCP connections, one for data and another control
3. TELNET and FTP can only use TWO connections at a time

1. 1
2. 1 and 2
3. 2 and 3
4. 1, 2 and 3

Q. In an IPv6 header, the traffic class field is similar to the ________ field in the IPv4 header.

1. TOS field
2. Fragmentation field
3. Fast Switching
4. Option field

Q. Which among the following types of Server filters Website Traffic?

1. POP Server
2. Database Server
3. Proxy Server
4. Mail Server

Q. What is the minimum no. of wires required for sending data over a serial communication link?

1. 1
2. 3
3. 2
4. 4

Q. How many bits are required to encode all twenty six letters, ten symbols, and ten numerals?

1. 5
2. 6
3. 7
4. 46

Q. PGP encrypts data by using a block cipher called :

1. international data encryption algorithm
2. private data encryption algorithm
3. internet data encryption algorithm
4. none of the options

Q. Why is one-time password safe?

1. It is easy to generate
2. It cannot be shared
3. It is different for every access
4. It can be easily decrypted

Q. What is the value of acknowledgement field in a segment

1. Number of previous bytes to receive
2. Total number of bytes to receive
3. Number of next bytes to receive
4. Sequence of zero’s and one’s

Q. The address of a class B Host is to be split into subnets with a 3-bit subnet number. What is the maximum number of subnets and maximum number of hosts in each subnet?

1. 8 subnets and 262142 hosts
2. 6 subnets and 262142 hosts
3. 6 subnets and 1022 hosts
4. 8 subnets and 1024 hosts

Q. Identify the subnet mask for the given direct broadcast address of subnet is 205.15.16.31

1. 255.255.192.192
2. 255.255.255.198
3. 255.255.255.240
4. 255.255.257.240

Q. You have a network ID of 192.168.10.0 and require at least 25 host IDs for each subnet, with the largest amount of subnets available. Which subnet mask should you assign?

1. 255.255.255.192
2. 255.255.255.224
3. 255.255.255.240
4. 255.255.255.248

Q. In context of TCP/IP computer network models, which of the following is FALSE?

1. Besides span of geographical area, the other major difference between LAN and WAN is that the later uses switching element.
2. A repeater is used just to forward bits from one network to another one.
3. IP layer is connected oriented layer in TCP/IP.
4. A gateway is used to connect incompatible networks.

Q. ________ transport layer protocol is used to support electronic mail

1. SNMP
2. IP
3. SMTP
4. TCP

Q. Time to Live(TTL) field in the IP datagram is used __

1. to optimize throughput
2. to prevent packet looping
3. to reduce delays
4. to prioritize packets

Q. Correct expression for UDP user datagram length is

1. length of UDP = length of IP-length of IP header’s
2. length of UDP= length of UDP-length of UDP header’s
3. length of UDP = length of IP+length of IP header’s
4. length of UDP = length of UDP+length of UDP header’s

Q. Which of the following would not be specified in a communication protocol?

1. Header contents
2. Trailer contents
3. Error Checking
4. Data content of message