Test 1 - Computer Network | Computer Science (CS)

Description: GATE Previous year Topic Wise Solution | Computer Network - 1
Number of Questions: 14
Created by:
Tags: GATE CS Computer Network
Attempted 0/14 Correct 0 Score 0

How many 8-bit characters can be transmitted per second over a 9600 baud serial communication link using asynchronous mode of transmission with one start bit, eight data bits, and one parity bit?

  1. 600

  2. 800

  3. 876

  4. 1200


Correct Option: B
Explanation:

Choose the best matching Group 1 and Group 2.

  1. P-1, Q-2, R-3

  2. P-2, Q-3, R-1

  3. P-2, Q-3, R-1

  4. P-1, Q-3, R-2


Correct Option: A
Explanation:

Transport layer is responsible for end to end communication, creation of sockets. Network layer routes the data from one node to other, till it reach to destination. Datalink layer ensures reliable data transfer by error correction, duplication check ordered delivery etc. P − 1,Q − 2,R − 3

The routing table of a router is shown below:

On which interface will the router farward packets addressed to destinations 128.75.43.16 and 192.12.17.10 respectively?

  1. Eth 1 and Eth 2

  2. Eth 0 and Eth 2

  3. Eth 0 and Eth 3

  4. Eth 1 and Eth 3


Correct Option: C
Explanation:

Which of the following is NOT true with respective to a transparent bridge and a router?

  1. Both bridge and router selectively farward data packets

  2. A bridge uses IP addresses while a router uses MAC addresses

  3. A bridge builds up its routing table by inspecting incoming packets

  4. A router can connect between a LAN and a WAN.


Correct Option: B
Explanation:

Bridge is the device which work at data link layer whereas router works at network layer. Both selectively forward packets, build routing table & connect between LAN & WAN but since bridge works at data link it uses MAC addresses to route whereas router uses IP addresses.

The address resolution protoc0l (ARP) is used for

  1. Finding the IP address from the DNS

  2. Finding the IP address of the default gateway

  3. Finding the IP address that corresponds to a MAC address

  4. Finding the MAC address that corresponds to an IP address


Correct Option: D
Explanation:

Address resolution protocol is applied to determine MAC address corresponding to an IP address.

Packets of the same session may be routed through different paths in

  1. TCP, but not UDP

  2. TCP and UDP

  3. UDP but not TCP

  4. Neither TCP, nor UDP


Correct Option: D
Explanation:

Selection of any path during routing of a packet is done at Network layer not at transport layer, So TCP & UDP both have nothing to do with this.

In a network of LANs connected by bridges, packets are set from one LAN to another through intermediate bridges. Since more than one path may exist between two LANs, packets may have to be routed through multiple bridges. Why is the spanning tree algorithm used for bridge-routing?

  1. For shortest path routing between LANs

  2. For avoiding loops in the routing paths

  3. For fault tolerance

  4. For minimizing collisions


Correct Option: B
Explanation:

Spanning tree algorithm for a graph is applied to find a tree free of cycles, so in this network we apply spanning tree algorithm to remove loops in routing paths.

Consider three IP networks A, B and C. Host HA in network A send messages each containing 180 bytes of application data to a host HC in network C. The TCP layer prefixes a 20 byte header to the message. This passes through an intermediate network B. The maximum packet size, including 20 byte IP header, in each network is A :1000 bytes B :100 bytes C :1000 bytes The network A and B are connected through a 1 Mbps link, while B and C are connected by a 512 Kbps link (bps=bits per second).

What is the rate at which application data is transferred to host Hc? Ignore errors, acknowledgements, and other overheads.

  1. 325.5 Kbps

  2. 354.5 Kbps

  3. 409.6 Kbps

  4. 512.0 Kpps


Correct Option: B
Explanation:

The maximum window size for data transmission using the selective reject protocol with n-bit frame sequence numbers is

  1. 2n

  2. 2n−1

  3. 2n − 1

  4. 2n−2


Correct Option: B
Explanation:

n bit frame sequence nos are used so possible are 2n nos. But sending & receiving window together so $\dfrac{2^n}{2} = 2^{n-1}$

A and B are the only two stations on an Ethernet. Each has a steady queue of frames to send. Both A and B attempt to transmit a frame, collide, and A wins the first backoff race, At the end of this successful transmission by A, both A and B attempt to transmit and collide. The probability that A wins the second backoff race is

  1. 0.5

  2. 0.625

  3. 0.75

  4. 1.0


Correct Option: B
Explanation:

In a packet switching network, packets are routed from source to destination along a single path having two intermediate node. If the message size is 24 bytes and each packet contains a header of 3 bytes, then the optimum packet size is

  1. 4

  2. 6

  3. 7

  4. 9


Correct Option: D
Explanation:

Suppose the round trip propagation delay for a 10 Mbps Ethernet having 48-bit jamming signal is 46.4 ىs . The minimum frame size is:

  1. 94

  2. 416

  3. 464

  4. 512


Correct Option: D
Explanation:

An organization has a class B network and wishes to form subnets for 64 departments. The subnet mask would be

  1. 255.255.0.0

  2. 255.255.64.0

  3. 255.255.128.0

  4. 255.255.252.0


Correct Option: D
Explanation:

Class B has subnet mask = 255.255.0.0 We require 64 more subnets so 26. 6 bits are required. 255.255.11111100.00000000 255.255. 252.0

Consider three IP networks A, B and C. Host HA in network A send messages each containing 180 bytes of application data to a host HC in network C. The TCP layer prefixes a 20 byte header to the message. This passes through an intermediate network B. The maximum packet size, including 20 byte IP header, in each network is A :1000 bytes B :100 bytes C :1000 bytes The network A and B are connected through a 1 Mbps link, while B and C are connected by a 512 Kbps link (bps=bits per second).

Assuming that the packets are correctly delivered, how many bytes, including headers, are delivered to the IP layer at the destination for one application message, in the best case ? Consider only data packets.

  1. 200

  2. 220

  3. 240

  4. 260


Correct Option: D
Explanation:

At A Data + Header = 200 bytes. This would require only 1 packet of N/W A At B 200 bytes of payload from network A is packed in 80 payload + 20 header packet. This would require 20+80 20 + 80 20+40 Packets total 260 bytes. These are transferred to C

- Hide questions