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DSSSB TGT / PGT · Computer Science

Computer Networks Previous Year Questions (page 4)

173 Computer Networks (Computer Science) questions asked in DSSSB TGT / PGT previous year papers, each with the correct answer and explanation. Read them free on UTpaper, or attempt the full papers as timed online tests.

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Q151DSSSB TGT Computer Science, 24 Jun 2023, Shift 3 (4:30 PM)
Which of the following statements is FALSE about TCP (Transmission control protocol)?
  1. AIt uses a three-way handshake to establish a connection.
  2. BIt receives data from application as a single stream.
  3. CIt is a connection-oriented protocol.
  4. DIt is a connection-less protocol.
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Correct answer: (D) It is a connection-less protocol.

Explanation

TCP is connection-oriented (it uses a three-way handshake), so calling it connection-less is false. UDP is the connection-less protocol.

Q152DSSSB TGT Computer Science, 24 Jun 2023, Shift 3 (4:30 PM)
Which of the following statements is true about slow start phase of the TCP congestion control?
  1. ACongestion window increases by 1 Maximum Segment Size every round trip time.
  2. BCongestion window approximately doubles every round trip time.
  3. CCongestion window increases by 2 Maximum Segment Size on every successful acknowledgement.
  4. DCongestion window approximately doubles on every successful acknowledgement.
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Correct answer: (B) Congestion window approximately doubles every round trip time.

Explanation

In slow start, cwnd grows by 1 MSS for each ACK, which roughly doubles the window every round-trip time until it reaches the threshold.

Q153DSSSB TGT Computer Science, 24 Jun 2023, Shift 3 (4:30 PM)
The refractive index of the core of an optical fibre is greater than that of cladding because:
  1. Alight gets reflected at the entrance end of the optical fibre
  2. Bthe light gets totally internally reflected into the core
  3. Clight gets restricted at the entrance end of the optical fibre
  4. Dthe light gets refracted into cladding
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Correct answer: (B) the light gets totally internally reflected into the core

Explanation

Light stays in a denser core because rays hitting the core-cladding boundary above the critical angle undergo total internal reflection.

Q154DSSSB TGT Computer Science, 7 Feb 2024, Shift 2 (12:30 PM)
In computer networking, a Repeater is a device that operates only in the ______ layer.
  1. APhysical
  2. BNetwork
  3. CData link
  4. DSession
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Correct answer: (A) Physical

Explanation

A repeater only regenerates the signal bit by bit, without reading addresses or frames, so it works only at the physical layer.

Q155DSSSB TGT Computer Science, 7 Feb 2024, Shift 2 (12:30 PM)
A semaphore is an integer variable that, apart from initialization, is accessed only through which of the following standard atomic operation?
  1. Arelease ( )
  2. Block ( )
  3. Cacquire ( )
  4. Dsignal ( )
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Correct answer: (D) signal ( )

Explanation

A semaphore is accessed, apart from initialisation, only through the atomic operations wait() (P) and signal() (V).

Q156DSSSB TGT Computer Science, 7 Feb 2024, Shift 2 (12:30 PM)
Which of the following statement(s) is/are correct for context switching in Operating System? I. When a context switch occurs, the kernel saves the context of the old process in its PCB (Process Control Block). II. Context-Switch time is pure overhead, because the system does no useful work while switching.
  1. ANeither I nor II
  2. BOnly I
  3. COnly II
  4. DBoth I and II
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Correct answer: (D) Both I and II

Explanation

During a context switch the kernel saves the old process state in its PCB and loads the new one's. This switching time is pure overhead, since no useful work is done. Both are correct.

Q157DSSSB TGT Computer Science, 7 Feb 2024, Shift 2 (12:30 PM)
Which of the following statement is correct regarding unguided media (wireless)? I. Unguided media transport electromagnetic waves without using a physical conductor. II. Unguided signals can travel from the source to destination in ground propagation way.
  1. AOnly II
  2. BBoth I and II
  3. COnly I
  4. DNeither I nor II
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Correct answer: (B) Both I and II

Explanation

Unguided (wireless) media carry electromagnetic waves without a physical conductor, and these signals can travel by ground, sky or line-of-sight propagation. Both are correct.

Q158DSSSB TGT Computer Science, 7 Feb 2024, Shift 2 (12:30 PM)
Which of the following is correct formula for calculating wavelength (λ) of a signal in the data communication?
  1. Aλ = propagation speed + frequency
  2. Bλ = propagation speed × period
  3. Cλ = propagation speed + period
  4. Dλ = propagation speed × frequency
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Correct answer: (B) λ = propagation speed × period

Explanation

Wavelength = propagation speed × period, which equals propagation speed / frequency.

Q159DSSSB TGT Computer Science, 7 Feb 2024, Shift 2 (12:30 PM)
Which of the following type of guided transmission media are categorized by their Radio Government (RG) ratings in computer networking?
  1. AFiber-Optic Cable
  2. BCoaxial Cable
  3. CMetallic Cable
  4. DTwisted-Pair Cable
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Correct answer: (B) Coaxial Cable

Explanation

Coaxial cables are classified by Radio Government (RG) ratings such as RG-59 and RG-58, which define their physical specifications.

Q160DSSSB TGT Computer Science, 25 Jun 2023, Shift 3 (4:30 PM)
Which service is NOT provided by web servers?
  1. AServing web pages
  2. BResource sharing
  3. CServer side scripting
  4. DRunning gateway programs
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Correct answer: (B) Resource sharing

Explanation

Web servers serve pages, run server-side scripts and run gateway (CGI) programs. Sharing resources such as files and printers is the job of file or print servers.

Q161DSSSB TGT Computer Science, 25 Jun 2023, Shift 3 (4:30 PM)
Which of the following fields in the IPV4 header ensures that datagrams do NOT circulate forever (due to, for example, a long-lived routing loop) in the network?
  1. AService time
  2. BTime-to-live
  3. CType of service
  4. DHeader checksum
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Correct answer: (B) Time-to-live

Explanation

TTL is decremented at each router, and the datagram is discarded when it reaches 0. This stops packets from looping forever.

Q162DSSSB TGT Computer Science, 25 Jun 2023, Shift 3 (4:30 PM)
What is the purpose of a relational database management system (RDBMS)?
  1. ATo store and manage data in a structured format using tables, columns and rows
  2. BTo store and manage data in a network format using graphs and edges
  3. CTo store and manage data in a hierarchical format using trees and nodes
  4. DTo store and manage data in an unstructured format using tags and categories
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Correct answer: (A) To store and manage data in a structured format using tables, columns and rows

Explanation

An RDBMS stores data in tables (relations) made of rows and columns, and uses keys to relate the tables.

Q163DSSSB TGT Computer Science, 25 Jun 2023, Shift 3 (4:30 PM)
On which two different modes does IPSec operate?
  1. ATransport; tunnel
  2. BTransport; network
  3. CTunnel; surface
  4. DNone of the given options
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Correct answer: (A) Transport; tunnel

Explanation

IPSec works in transport mode, which protects only the payload, and tunnel mode, which encapsulates and protects the entire IP packet.

Q164DSSSB TGT Computer Science, 25 Jun 2023, Shift 3 (4:30 PM)
Which are the two basic cellular systems?
  1. ANone of the given options
  2. BCircuit-switched system and packet-switched system
  3. CCounter switched system and packet-switched system
  4. DWired and wireless
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Correct answer: (B) Circuit-switched system and packet-switched system

Explanation

Cellular networks are of two basic kinds: circuit-switched (e.g. GSM voice) and packet-switched (e.g. GPRS, LTE data).

Q165DSSSB TGT Computer Science, 25 Jun 2023, Shift 2 (12:30 PM)
is the standard that defines how web servers and application programs communicate.
  1. AJDBC
  2. BODBC
  3. CCGI
  4. DHTTP
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Correct answer: (D) HTTP

Explanation

Note: the answer key gives (D), but the standard that defines how a web server passes requests to application programs and gets their output back is CGI (Common Gateway Interface). HTTP defines communication between browsers and web servers.

Q166DSSSB TGT Computer Science, 25 Jun 2023, Shift 2 (12:30 PM)
______ is the handover from a satellite network to a terrestrial cellular network.
  1. AGateway handover
  2. BInter satellite handover
  3. CInter system handover
  4. DIntra satellite handover
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Correct answer: (C) Inter system handover

Explanation

Handover between two different kinds of network, such as a satellite network and a terrestrial cellular network, is called inter-system handover. Intra- and inter-satellite handovers happen within the satellite system.

Q167DSSSB TGT Computer Science, 25 Jun 2023, Shift 2 (12:30 PM)
Which of the following are networking transport layer protocols?
  1. AFTP and DNS
  2. BTelnet and ICMP
  3. CTCP, UDP and SCTP
  4. DARP and RARP
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Correct answer: (C) TCP, UDP and SCTP

Explanation

TCP (connection-oriented), UDP (connectionless) and SCTP (stream control) all work at the transport layer. FTP, DNS and Telnet are application-layer protocols, ICMP is network-layer, and ARP/RARP work between the network and link layers.

Q168DSSSB TGT Computer Science, 25 Jun 2023, Shift 2 (12:30 PM)
The internet layer in TCP/IP model is associated with ______ data.
  1. Asegments
  2. Bframes
  3. Cbytes
  4. Dpackets
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Correct answer: (D) packets

Explanation

The TCP/IP internet layer (IP) handles packets, also called datagrams. The transport layer uses segments, and the network access (link) layer uses frames.

Q169DSSSB TGT Computer Science, 25 Jun 2023, Shift 2 (12:30 PM)
Which of the following are the most essential components a computer system uses for communication over internet?
  1. AApplications and mouse
  2. BMonitor and keyboard
  3. CNIC and TCP/IP
  4. DCamera and microphone
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Correct answer: (C) NIC and TCP/IP

Explanation

To communicate over the Internet, a computer needs a Network Interface Card (the hardware connection) and the TCP/IP protocol suite (rules for addressing and transmitting data). The other items are peripherals.

Q170DSSSB TGT Computer Science, 25 Jun 2023, Shift 2 (12:30 PM)
Communication between an application program and a database server occur via:
  1. AODBC OR JDBC
  2. BAPI
  3. Cweb server
  4. DHTTP
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Correct answer: (A) ODBC OR JDBC

Explanation

Application programs talk to database servers through standard database APIs: ODBC (Open Database Connectivity) or JDBC for Java. These drivers send SQL queries and return results.

Q171DSSSB TGT Computer Science, 25 Jun 2023, Shift 2 (12:30 PM)
Which of the following is NOT a network layer function?
  1. AError control and flow control
  2. BIntra-routing
  3. CRouting
  4. DCongestion control
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Correct answer: (A) Error control and flow control

Explanation

Error control and flow control between adjacent nodes are data link layer functions, and end-to-end versions belong to the transport layer. Routing and congestion control are network layer functions.

Q172DSSSB TGT Computer Science, 25 Jun 2023, Shift 2 (12:30 PM)
Which of the following 4-byte IP addresses are used for internet protocol layer?
  1. ANetwork address and port address
  2. BNetwork address and MAC address
  3. CNetwork address and host address
  4. DHost address and port address
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Correct answer: (C) Network address and host address

Explanation

An IPv4 address (4 bytes) has two parts: a network address that identifies the network and a host address that identifies the device on it. Port and MAC addresses belong to other layers.

Q173DSSSB TGT Computer Science, 25 Jun 2023, Shift 2 (12:30 PM)
Which layer is responsible for sending data as a bit stream?
  1. APresentation layer
  2. BNetwork layer
  3. CPhysical layer
  4. DData link layer
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Correct answer: (D) Data link layer

Explanation

Note: the answer key gives (D), but transmitting raw data as a bit stream over the physical medium is the job of the physical layer (C). The data link layer works with frames.

How to use these DSSSB TGT / PGT Computer Science questions

Every question here was asked in a real DSSSB TGT / PGT paper; the paper and shift are shown on the card, and the number opens the question on its own page. Try each one before tapping Show answer, then attempt the full DSSSB TGT / PGT papers as timed tests to check your speed under exam conditions.

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