UGC NET Computer Science Data Communication and Computer Networks Previous Year Questions (PYQs)
Practise 45 Data Communication and Computer Networks questions asked in UGC NET Computer Science from 2020–2025. Questions cover Transmission media, Error detection and correction, OSI reference model and the TCP/IP protocol suite, Data link layer, Medium access control and Network layer. Every question is shown with its options and the correct answer, free to read.
45 PYQs2020–2025Answers includedFree
Practise Data Communication and Computer Networks as timed sets
Focused 10-question sets with instant scoring, explanations, and weak-area analysis.
The primary function of a firewall in network security is
Ato monitor network traffic and detect anomalies
Bto create virtual private networks for secure communication
Cto filter incoming and outgoing network traffic based on security rules
Dto encrypt data before transmission
Answer:(C)to filter incoming and outgoing network traffic based on security rules
Explanation
A firewall enforces access-control rules by allowing, denying or inspecting traffic at a network boundary. VPN creation, intrusion detection and encryption are separate security functions. The correct option follows from the stated definition or calculation; the other options omit a necessary condition or describe a different concept.
Compare corresponding bit positions: the second, fourth and fifth bits differ. Hence three substitutions are needed, so the Hamming distance is 3. The correct option follows from the stated definition or calculation; the other options omit a necessary condition or describe a different concept.
A. Service-level agreement B. Virtualisation C. Internet of Things D. Platform as a service
I. Connecting physical devices over the Internet II. Development environment over the Internet III. Contracts specifying performance and availability IV. Multiple operating systems on one physical server
AA-III, B-II, C-I, D-IV
BA-III, B-IV, C-I, D-II
CA-III, B-I, C-IV, D-I
DA-I, B-IV, C-III, D-II
Answer:(B)A-III, B-IV, C-I, D-II
Explanation
A service-level agreement specifies performance and availability, virtualisation permits multiple operating systems on one physical server, IoT connects physical devices, and PaaS provides an online development/deployment platform.
A. In connection-oriented service, the destination address is specified only during connection setup.
B. Packet sequencing is not guaranteed in connection-oriented service.
C. Flooding sends an incoming packet on every outgoing line except the arrival line.
D. The presentation layer performs error detection and recovery.
AA, B and C only
BB, C and D only
CA and C only
DA, C and D only
Answer:(C)A and C only
Explanation
Connection-oriented delivery keeps connection state and preserves ordering, so B is false. Flooding is correctly described by C, and error recovery belongs to lower layers rather than the presentation layer; hence A and C are correct.
A. DHCP ACK
B. DHCP DISCOVER
C. DHCP OFFER
D. DHCP REQUEST
E. Client receives IP configuration
AA, B, C, D, E
BB, C, D, A, E
CC, B, A, E, D
DD, A, E, C, B
Answer:(B)B, C, D, A, E
Explanation
DHCP follows the DORA exchange: Discover, Offer, Request, Acknowledge, then the client applies the received configuration. This is B, C, D, A, E. The correct option follows from the stated definition or calculation; the other options omit a necessary condition or describe a different concept.
Identify the correct statements about multiple access techniques.
A. ALOHA is used for multiple access on a shared medium.
B. TDMA uses Walsh tables for time-slot allocation.
C. CSMA/CD was invented for wireless networks.
D. CDMA codes are sequences generated by orthogonal codes.
AA and B only
BB and C only
CC and D only
DA and D only
Answer:(D)A and D only
Explanation
ALOHA is a shared-medium multiple-access scheme and CDMA uses orthogonal spreading codes. Walsh codes are associated with CDMA, while CSMA/CD was designed for wired Ethernet, not wireless networks.
I. Retrieves email from a mail server II. Remote login over a network III. Maps IP addresses to MAC addresses on a LAN IV. Accesses email on the server without downloading
AA-II, B-I, C-III, D-IV
BA-III, B-IV, C-I, D-II
CA-IV, B-III, C-I, D-II
DA-IV, B-III, C-II, D-I
Answer:(C)A-IV, B-III, C-I, D-II
Explanation
IMAP accesses email on the server without downloading it; ARP maps IP addresses to MAC addresses; POP retrieves email; TELNET provides remote login. The correct option follows from the stated definition or calculation; the other options omit a necessary condition or describe a different concept.
Sequence the following stages of the sliding-window protocol for flow control.
A. Sender moves the window to the next set of frames.
B. Sender sends a window of frames.
C. Receiver acknowledges the received frames.
D. If acknowledgement is not received, sender retransmits the frame.
AB, A, C, D
BB, C, D, A
CB, D, C, A
DB, C, A, D
Answer:(D)B, C, A, D
Explanation
The sender sends a window, the receiver acknowledges it, and the sender advances its window. Retransmission is the fallback when an acknowledgement is not received, giving B, C, A, D. The correct option follows from the stated definition or calculation; the other options omit a necessary condition or describe a different concept.
Consider a noiseless channel with bandwidth 5000 Hz transmitting a signal with two signal levels. The maximum bit rate is
A2500 bps
B10000 bps
C5000 bps
D20000 bps
Answer:(B)10000 bps
Explanation
By Nyquist’s formula, maximum bit rate = 2B log₂L = 2 × 5000 × log₂2 = 10000 bps. The correct option follows from the stated definition or calculation; the other options omit a necessary condition or describe a different concept.
A CSMA/CD network has bandwidth 20 Mbps. If maximum propagation time is 25 μs, what is the minimum frame size?
A500 bits
B1000 bits
C1500 bits
D2000 bits
Answer:(B)1000 bits
Explanation
For collision detection, a frame must last at least the round-trip propagation time: 2 × 25 μs. At 20 Mbps this is 20×10⁶ × 50×10⁻⁶ = 1000 bits. The correct option follows from the stated definition or calculation; the other options omit a necessary condition or describe a different concept.
Which of the following are key features of Mobile Ad hoc Networks (MANETs)?
A. Self-organizing and decentralized
B. High mobility of nodes
C. Requires fixed infrastructure for operation
D. Network topology is dynamic and constantly changing
E. Requires a central controller to manage network traffic
AA, B and E only
BB, C, D and E only
CA, B and D only
DA, B and C only
Answer:(C)A, B and D only
Explanation
MANETs are infrastructure-free, decentralized and self-organizing, with mobile nodes and changing topology. They do not require a fixed infrastructure or a central controller. The correct option follows from the stated definition or calculation; the other options omit a necessary condition or describe a different concept.
In a token ring network the transmission speed is 10⁷ bps and the propagation speed is 200 m/μs. The 1-bit delay in this network is equivalent to ________________
A20 m
B30 m
C50 m
D40 m
Answer:(A)20 m
Explanation
The transmission speed is 10⁷ bps, so one bit occupies 1/10⁷ s = 0.1 μs on the wire. In that time the signal advances 0.1 μs × 200 m/μs = 20 m. The 1-bit delay is therefore equivalent to 20 metres of cable, so option A is correct.
Consider a CSMA/CD network that transmits
data at the rate of 100 Mbps over a 1 Kilometre
cable with no repeater. If the minimum frame size
required for this network is 1250 bytes, what is
the signal speed (km/sec) in the cable.
A8000
B16000
C12000
D20000
Answer:(D)20000
Explanation
The minimum frame of 1250 bytes is 10,000 bits, which at 100 Mbps takes 10,000/10⁸ = 10⁻⁴ s to transmit. Collision detection requires that time to cover the round trip of 2 × 1 km. The signal speed is therefore 2 km / 10⁻⁴ s = 20,000 km/s — option D.
Host A (on TCP/IPv4 Networks) send an IP
Datagram D to host B (also on TCP/IPv4 network).
Assume that no error occurred during
transmission of D, when D reaches B. Which of
following header field may differ from that of
original datagram D ?
A. TTL
B. Checksum
C. Fragment offset
D. Source IP
E. Destination IP
A(A) and (B) Only
B(A), (B) and (C) Only
C(A), (B), (C) and (D) Only
D(A), (B), (C) and (E) Only
Answer:(B)(A), (B) and (C) Only
Explanation
TTL is decremented by every router, so (A) changes. The header checksum covers TTL and must be recomputed at each hop, so (B) changes. Fragment offset changes whenever the datagram is fragmented in transit, so (C) may differ. Source and destination IP are never rewritten by ordinary routing, so (D) and (E) stay fixed. Only (A), (B) and (C) — option B.
Arrange the following steps in a proper sequence
for the typical process of a DNS query :
A. Query authoritative DNS Server
B. Query local DNS Server
C. Local DNS Server Check Cache
D. Query root DNS Server
E. Query TLD DNS Server
A(A), (C), (E), (B), (D)
B(E), (A), (C), (B), (D)
C(A), (B), (C), (D), (E)
D(B), (C), (D), (E), (A)
Answer:(D)(B), (C), (D), (E), (A)
Explanation
Resolution starts at the local recursive resolver (B), which first checks its cache (C). On a miss it queries a root server (D), which refers it to the TLD server (E), which in turn refers it to the authoritative server (A) holding the record. That order is option D.
A class B network on the Internet has a subnet
mask of 255.255.248.0, what is the maximum
number of hosts per subnet?
A1022
B1023
C2046
D2047
Answer:(C)2046
Explanation
The mask 255.255.248.0 is 11111111.11111111.11111000.00000000, leaving 11 zero bits for the host field. That gives 2¹¹ = 2048 addresses per subnet, less the network and broadcast addresses, so 2046 usable hosts — option C.
Consider the three way hand shaking process
followed during TCP connection establishment
between two hosts A and B . Let S and R be two
random 32 -bit starting sequence numbers
chosen by A and B, respectively. Suppose A
sends a TCP segment having SYN bit =1, SEQ
number = S and ACK bit =0 and B accepts the
connection request.
Which one of the following choices represents
the information present in the TCP segment
header that is sent by B to A ?
ASYN bit =1, SEQ number =S+1, ACK bit =0, ACK number =R, FiN bit =0
BSYN bit =0, SEQ number =R, ACK bit =1, ACK number =S+1, FiN bit =0
CSYN bit =1, SEQ number =R, ACK bit =1, ACK number =S+1, FiN bit =0
DSYN bit =1, SEQ number = R, ACK bit =1, ACK number =S, FiN bit =0
Answer:(C)SYN bit =1, SEQ number =R, ACK bit =1, ACK number =S+1, FiN bit =0
Explanation
B’s reply is a SYN-ACK. It carries B’s own initial sequence number R, sets SYN = 1 because B is opening its own direction of the connection, sets ACK = 1, and acknowledges A’s stream with ACK number S + 1. FIN stays 0. Option C matches all five fields.
Two computers A and B are configured as follows
: A has IP address 203.197.2.53 and subnet mask
255.255.128.0, B has IP address 203.197.75.201
and subnet mask 255.255.192.0. What one of the
following statement is true?
AA and B both assume they are on the same network
BB assumes, A is on same network, A assumes B is on different network
CA assumes, B is on same network, but B assumes, A is on a different network
DA and B both assume they are on different network
Answer:(C)A assumes, B is on same network, but B assumes, A is on a different network
Explanation
A applies its own mask to both addresses: 203.197.2.53 and 203.197.75.201 both reduce to 203.197.0.0, so A concludes B is local. B applies its own mask: its address reduces to 203.197.64.0 but A’s reduces to 203.197.0.0, so B concludes A is remote. Option C describes exactly this asymmetry.
A. In IPv4 addressing, a block of address can be
define as x.y.z.t/ n in which x.y.z.t define one of
the address and / n define the mask
B. The first address in the block can be found by
setting the rightmost 32-n bits to 0s
C. Address of class C is used for multicast
communication
D. There are five classes in IPv4 address
E. Supernetting combine several networks into
one large network
A(A), (B) and (C) Only
B(A), (B), (D) and (E) Only
C(A), (C), (D) and (E) Only
D(C), (D) and (E) Only
Answer:(B)(A), (B), (D) and (E) Only
Explanation
(A) is true — x.y.z.t/n names a block by one address and a prefix length. (B) is true — zeroing the rightmost 32 − n bits yields the first address of the block. (D) is true — IPv4 defines classes A through E. (E) is true — supernetting aggregates contiguous blocks into one larger route. (C) is false: multicast uses class D, not class C. So (A), (B), (D) and (E) — option B.
Has functions are used to produce the message digests which are then encrypted with a private key to get:
APublic key
BDigital signature
CCipher text
DData Encryption Standard
Answer:(B)Digital signature
Explanation
The key idea is stated in the problem: Has functions are used to produce the message digests which are then encrypted with a private key to get:. The correct answer is B: Digital signature. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
A multiplexes combines for 100 Kbps channels using a time slot of 2 bits. What is the bit rate ?
A100 Kbps
B200 Kbps
C40 Kbps
D1000 Kbps
Answer:(C)40 Kbps
Explanation
The key idea is stated in the problem: A multiplexes combines for 100 Kbps channels using a time slot of 2 bits. What is the bit rate ?. The correct answer is C: 40 Kbps. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
Which of the following is not a field in TCP header ?
ASequence Number
BChecksum
CFregmentation offset
DWindow size
Answer:(C)Fregmentation offset
Explanation
The key idea is stated in the problem: Which of the following is not a field in TCP header ?. The correct answer is C: Fregmentation offset. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
In "bit stuffing", each frame begins and ends with a bit pattern in hexadecimal ?
AOx8c
BOx6F
COxEF
DOx7E
Answer:(D)Ox7E
Explanation
The key idea is stated in the problem: In "bit stuffing", each frame begins and ends with a bit pattern in hexadecimal ?. The correct answer is D: Ox7E. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
Which of the following are example of CSMA channel sensing methods ?
A. 1-persistent
B. 2-persistent
C. p-persistent
D. o-persistent Choose the correct answer from the options given below :
The work done by UDP is/are :
A. Congestion control
B. Flow control
C. Retransmission
D. Segments transmission Choose the correct answer from the options given below : (Q)
A. and
D. Only
AA and D only
BC only
CD only
DB and C only
Answer:(C)D only
Explanation
The key idea is stated in the problem: The work done by UDP is/are :
A. Congestion control
B. Flow control
C. Retransmission
D. Segments transmission Choose the correct answer from the options given below : (Q)
A. and
D. Only. The correct answer is C: D only. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
Which of the following statement/s is/are NOT CORRECT ?
A. OSPF is based on distance-vector routing protocol.
B. Both link-state and distance-vector routing are based on the least cost goal.
C. BGP4 is based on the path-vector algorithm.
D. The three-node instability can be avoided using split horizon combined with poison reverse.
E. _ RIP is based on link state algorithm. Choose the correct answer from the options given below :
The key idea is stated in the problem: Which of the following statement/s is/are NOT CORRECT ?
A. OSPF is based on distance-vector routing protocol.
B. Both link-state and distance-vector routing are based on the least cost goal.
C. BGP4 is based on the path-vector algorithm.
D. The three-node . The correct answer is A: (A), (D) and &) Only. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
Which of the following statement/s are CORRECT ?
A. NRZ is a bipolar scheme in which the positive voltage define bit is 0 (zero).
B. NRZ-L and NRZ-I both have an average signal rate of N/2.
C. The idea of RZ and NRZ-L are combined into Manchester scheme.
D. NRZ-L and NRZ-I both have DC component problems.
E. The minimum bandwidth of Manchester and differential Manchester is 3 times that of NRZ. Choose the correct answer from the options given below :
Which of the following are commonly used parsing techniques in NLP (Natural Language Processing) for syntatic analysis.
A. Top down parsing
B. Bottom Up parsing
C. Dependency parsing
D. _ Statistical machine translation
E. Earley parsing Choose the correct answer from the options given below :
Evaluate these statements: Statement I: If H is non empty finite subset of a group G and abeH V a, beH, then H is also a group. Statement II: There is no homomorphism exist from (Z, +) to (Q, +); where Z is set of integers and Q is set of rational number. In the light of the above statements, choose the most appropriate answer from the options given below :
ABoth Statement I and Statement II are correct
BBoth Statement I and Statement II are incorrect
CStatement I is correct but Statement II is incorrect
DStatement I is incorrect but Statement II is correct
Answer:(C)Statement I is correct but Statement II is incorrect
Explanation
The key idea is stated in the problem: Evaluate these statements: Statement I: If H is non empty finite subset of a group G and abeH V a, beH, then H is also a group. Statement II: There is no homomorphism exist from (Z, +) to (Q, +); where Z is set of integers and Q is set of rational number. In t. The correct answer is C: Statement I is correct but Statement II is incorrect. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
Evaluate these statements: Statement I: A thread is a dispatchable unit of work that does not executes sequentially and is not interruptible Statement II: It is not possible to alter the behaviour of a thread by altering its context when thread is suspended. In the light of the above statements, choose the most appropriate answer from the options given below :
ABoth Statement I and Statement II are correct
BBoth Statement I and Statement II are incorrect
CStatement I is correct but Statement II is incorrect
DStatement I is incorrect but Statement II is correct
Answer:(B)Both Statement I and Statement II are incorrect
Explanation
The key idea is stated in the problem: Evaluate these statements: Statement I: A thread is a dispatchable unit of work that does not executes sequentially and is not interruptible Statement II: It is not possible to alter the behaviour of a thread by altering its context when thread is suspended. I. The correct answer is B: Both Statement I and Statement II are incorrect. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
Evaluate these statements: Statement I: In Reuse Oriented Model, Modification of the old system parts appropriate to the new requirements. Statement II: In Reuse Oriented Model, Integration of the modified parts are not possible into the new systems. In the light of the above statements, choose the most appropriate answer from the options given below :
ABoth Statement I and Statement II are correct
BBoth Statement I and Statement II are incorrect
CStatement I is correct but Statement II is incorrect
DStatement I is incorrect but Statement II is correct
Answer:(C)Statement I is correct but Statement II is incorrect
Explanation
The key idea is stated in the problem: Evaluate these statements: Statement I: In Reuse Oriented Model, Modification of the old system parts appropriate to the new requirements. Statement II: In Reuse Oriented Model, Integration of the modified parts are not possible into the new systems. In the li. The correct answer is C: Statement I is correct but Statement II is incorrect. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
Evaluate these statements: Statement I: In datagram networks - routers hold state information about connections Statement II: In virtual circuit network- each virtual circuit requires router table space per connection In the light of the above statements, choose the most appropriate answer from the options given below :
ABoth Statement I and Statement II are correct
BBoth Statement I and Statement II are incorrect
CStatement I is correct but Statement II is incorrect
DStatement I is incorrect but Statement II is correct
Answer:(D)Statement I is incorrect but Statement II is correct
Explanation
The key idea is stated in the problem: Evaluate these statements: Statement I: In datagram networks - routers hold state information about connections Statement II: In virtual circuit network- each virtual circuit requires router table space per connection In the light of the above statements, choo. The correct answer is D: Statement I is incorrect but Statement II is correct. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
Food X contains 6 units of Vitamin D per gram and 7 units of Vitamin E per gram and costs Rs. 12 per gram. Food Y contains 8 units of Vitamin D per gram and 12 units of Vitamin E per gram and costs Rs. 20 per gram. The daily minimum requirements of vitamin D and vitamin E are 100 units and 120 units respectively. Let x and y be the quantities in grams of Food X and Food Y.
AZ=6x+7y
BZ=8x+12y
CZ=12x +20y
DZ=20x+12y
Answer:(C)Z=12x +20y
Explanation
The key idea is stated in the problem: The cost funtion of total food is :. The correct answer is C: Z=12x +20y. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
Number of tuples by applying right outer join on relation X and Y is/are :
X (S, Si, C)
Y (S, P, D)
(J, 1, M)
(B, 2, N)
(R, 3, H)
(T, 4, G)
(J, S₁, CA)
(B, P₁, AB)
(R, D₁, DC)
(A, H₁, MD)
A16
B5
C3
D4
Answer:(D)4
Explanation
The key idea is stated in the problem: Number of tuples by applying right outer join on relation X and Y is/are :. The correct answer is D: 4. It follows the governing definition, algorithm, or calculation in this data communication and computer networks item; the other choices fail to satisfy one or more stated conditions.
Answer:(A)Worker node and master node respectively
Explanation
DataNodes store and serve HDFS data blocks on worker machines. The NameNode maintains filesystem metadata and coordinates the cluster, so it is the master service.
A code has valid words 0000000000, 0000011111, 1111100000, and 1111111111. If the received word is 0000000111, which word was sent?
A0000011111
B0000000000
C1111100000
D1111111111
Answer:(A)0000011111
Explanation
Decode by minimum Hamming distance. The received word differs from 0000011111 in two positions but from 0000000000 in three positions; the two words beginning with 11111 are farther away.
Using RSA with p = 3, q = 11, and d = 7, find e and encrypt 19.
A20, 19
B33, 11
C3, 28
D77, 28
Answer:(C)3, 28
Explanation
Here φ(n) = (3 − 1)(11 − 1) = 20. Since 7e ≡ 1 (mod 20), e = 3; with n = 33, encryption gives 19³ mod 33 = 28. Therefore option C is the only pair that has both the required inverse and ciphertext.
Protocols in which the sender sends one frame and waits for an acknowledgement before sending the next frame are called
ASimplex protocols
BUnrestricted simplex protocols
CSimplex stop-and-wait protocols
DRestricted simplex protocols
Answer:(C)Simplex stop-and-wait protocols
Explanation
Stop-and-wait allows only one outstanding frame, so the sender must wait for its acknowledgement. Sliding-window protocols, unlike stop-and-wait, permit multiple frames in transit.
The period of a signal is 100 ms. What is its frequency in kilohertz?
A10
B10⁷
C10⁻⁷
D10⁻²
Answer:(D)10⁻²
Explanation
The signal period is 100 ms, and frequency is its reciprocal. Because 100 ms = 0.1 seconds, its frequency is 1/0.1 = 10 Hz. Dividing by 1,000 converts this to 0.01 kHz = 10⁻² kHz; therefore the correct option is D.
Which statements about hash functions are true?
A. A hash function maps an arbitrary-length message to a fixed-length code.
B. It maps a fixed-length message to a variable-length code.
C. Distinct messages can have the same hash value.
A(A) only
B(B) and (C) only
C(A) and (C) only
D(B) only
Answer:(C)(A) and (C) only
Explanation
A fixed-size digest is produced from inputs of arbitrary size. Since the input space is much larger than the digest space, collisions—different inputs with the same digest—are possible.
For Post Office Protocol (POP), which statements are true?
A. POP has delete and keep modes.
B. In delete mode, mail is deleted from the mailbox after retrieval.
C. In delete mode, mail is deleted before retrieval.
D. In keep mode, mail is deleted before retrieval.
E. In keep mode, mail remains in the mailbox after retrieval.
A(A) and (B) only
B(A), (D), and (E) only
C(A), (B), (C), and (D) only
D(A), (B), and (E) only
Answer:(D)(A), (B), and (E) only
Explanation
POP can either retain server copies or delete them after successful retrieval. Thus A, B, and E are true; deletion before a client retrieves a message would defeat the protocol.
A firewall can filter packets using which fields?
A. Source IP address
B. Destination IP address
C. TCP source port
D. UDP source port
E. TCP destination port
A(A), (B), and (C) only
B(B) and (E) only
C(A), (C), and (D) only
D(A), (B), (C), (D), and (E)
Answer:(D)(A), (B), (C), (D), and (E)
Explanation
Packet filters can inspect network-layer source and destination addresses and transport-layer source and destination ports for TCP or UDP. Every listed field is therefore usable in a firewall rule.
Match List I with List II
List I List II
A. Serial Line IP (SLIP) (Application layer
B. Border Gateway Protocol (BGP) (I Transport layer
C. User Data Protocol (UDP) (I) Data Link layer
D. Simple Network Management (IV) Network layer
Protocol
List I
List II
Items are listed in the question stem.
Match each item to its stated description or complexity.
SLIP operates at the data-link layer, BGP at the network layer, UDP at the transport layer, and SNMP at the application layer; option B is the correct matching.
The laws of nature put two fundamental limits on data rate of a channel. The
H.Nyquist limit restricts the number of independent samples per second to
twice the band-width in a Noiseless channel.
Shannon's major result about noised channel is that maximum data rate of a
channel whose band width is H Hz, and whose signal-to-noise ratio is S/N is
given by:
Maximum number of bits/sec = H log2(1 + =)
In the light of the above statements. choose the correct answer from the options given below
ABoth Statement I and Statement II are true
BBoth Statement I and Statement II are false
CStatement I is correct but Statement II is false
DStatement I is incorrect but Statement II is true.
Answer:(A)Both Statement I and Statement II are true
Explanation
Nyquist limits a noiseless H-Hz channel to 2H independent samples per second. Shannon’s capacity formula is H log₂(1 + S/N), so both statements are true.
Given below are two statements:
Statement I: In Ceasar Cipher each letter of Plain text is replaced by another letter for
encryption.
Statement II: Diffie-Hellman algorithm is used for exchange of secret key.
In the light of the above statements, choose the correct answer from the options given below
(dd) Both Statement I and Statement II are true
AOCR review required
BBoth Statement I and Statement II are false
CStatement I is correct but Statement IT is false
DStatement I is incorrect but Statement II is true
Answer:(A)OCR review required
Explanation
A Caesar cipher substitutes each plaintext letter by a shifted letter. Diffie–Hellman establishes a shared secret over an insecure channel, so both statements are true.
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Frequently asked questions
How many Data Communication and Computer Networks questions have been asked in UGC NET Computer Science?
45 Data Communication and Computer Networks questions appear in the UGC NET Computer Science papers held between 2020–2025, and all of them are on this page with their answer key.
Are the answers on this page free?
Yes. Every question, its options, and the correct answer are free to read with no account. Signing in additionally unlocks the detailed explanation under each question.
Is Data Communication and Computer Networks an important topic for UGC NET Computer Science?
Data Communication and Computer Networks appears in every recent UGC NET Computer Science paper, across all 4 sittings covered here. Its share of the paper makes it worth revising thoroughly rather than sampling.
How should I practise Data Communication and Computer Networks after reading these questions?
Attempt the Data Communication and Computer Networks topic-wise sets, which put the same questions into a timed interface with instant scoring and weak-area analysis afterwards.