Computer Knowledge

Computer Networks

2,614 Questions

Computer networks involve the architecture, protocols, and security measures used for digital communication. This collection covers OSI model layers, IP addressing, data transmission, and cryptographic standards. These concepts are vital for the computer knowledge sections of banking and government exams.

OSI model layersNetwork protocolsIP subnet maskingData encryption standardsServer configurationsNetwork commands

Computer Networks Questions

Multiple choice

Two computers C1 and C2 are configured as follows. C1 has IP address 203.197.2.53 and netmask 255.255.128.0. C2 has IP address 203.197.75.201 and netmask 255.255.192.0. Which one of the following statements is true?

  1. C1 and C2 both assume they are on the same network

  2. C2 assumes C1 is on same network, but C1 assumes C2 is on a different network

  3. C1 assumes C2 is on same network, but C2 assumes C1 is on a different network

  4. C1 and C2 both assume they are on different networks.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Multiple choice

Consider the diagram shown below where a number of LANs are connected by (transparent) bridges. In order to avoid packets looping through circuits in the graph, the bridges organize themselves in a spanning tree. First, the root bridge is identified as the bridge with the least serial number. Next, the root sends out (one or more) data units to enable the setting up of the spanning tree of shortest paths from the root bridge to each bridge. Each bridge identifies a port (the root port) through which it will forward frames to the root bridge. Port conflicts are always resolved in favour of the port with the lower index value. When there is a possibility of multiple bridges forwarding to the same LAN (but not through the root port), ties are broken as follows: bridges closest to the root get preference and between such bridges, the one with the lowest serial number is preferred.

Consider the correct spanning tree for the previous question. Let host H1 send out a broadcast ping packet. Which of the following options represents the correct forwarding table on B3?

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Multiple choice

While opening a TCP connection, the initial sequence number is to be derived using a time-of-day (ToD) clock that keeps running even when the host is down. The low order 32 bits of the counter of the ToD clock is to be used for the initial sequence numbers. The clock counter increments once per millisecond. The maximum packet lifetime is given to be 64s. Which one of the choices given below is closest to the minimum permissible rate at which sequence numbers used for packets of a connection can increase?

  1. 0.015/s

  2. 0.064/s

  3. 0.135/s

  4. 0.327/s
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Multiple choice

Frames of 1000 bits are sent over a 106 bps duplex link between two hosts. The propagation time is 25 ms. Frames are to be transmitted into this link to maximally pack them in transit (within the link).

Suppose that the sliding window protocol is used with the sender window size of 2l, where l is the number of bits identified in the earlier part and acknowledgements are always piggy backed. After sending 2l frames, what is the minimum time the sender will have to wait before starting transmission of the next frame? (Identify the closest choice ignoring the frame processing time.)

  1. 16 ms

  2. 18 ms

  3. 20 ms

  4. 22 ms
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Multiple choice

One of the header fields in an IP datagram is the Time to Live (TTL) field. Which of the following statements best explains the need for this field?

  1. It can be used to prioritize packets.

  2. It can be used to reduce delays.

  3. It can be used to optimize throughput.

  4. It can be used to prevent packet looping.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The TTL (Time to Live) field in an IP datagram serves as a counter that gets decremented by 1 each time the packet passes through a router. When TTL reaches 0, the packet is discarded. This mechanism prevents packets from circulating indefinitely in routing loops - a packet cannot bounce forever because it will eventually expire. TTL has nothing to do with prioritization, delay reduction, or throughput optimization; its sole purpose is loop prevention.

Multiple choice

Which of the following security techniques also called bastion host essentially intrudes in the middle of the protocol exchange seeming like a destination in communication with the sender?

  1. Transport layer security

  2. Application proxy gateway

  3. Packet filtering gateway

  4. Sender authenticity

  5. Message integrity check
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This security technique also called bastion host essentially intrudes in the middle of this protocol exchange seeming like a destination in communication with the sender.