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

What statements are true about VLAN tagging (best answer)?

  1. Located after the destination MAC and Tag is always 0x0800

  2. It is located after the Ether Type

  3. Located after the source MAC and Tag is always 0x8100

  4. Located after the destination MAC and Tag is always 0x8100
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The 802.1Q VLAN tag is inserted after the source MAC address, and the Tag Protocol Identifier (TPID) is 0x8100.

Multiple choice

Which is true for Next Header field in an IPv6 header.

  1. 1 byte field that uses same protocol numbers as IPv4

  2. 1 byte field that uses different protocol numbers than IPv4

  3. 2 byte field that uses same protocol numbers as IPv4

  4. 2 byte field that uses different protocol numbers than IPv4
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Next Header field in IPv6 is 1 byte and uses the same protocol numbers as the Protocol field in IPv4.

Multiple choice

Which OSI layer and PDU are not correctly matched?

  1. Data Link - Frames

  2. Network - Packets

  3. Transport - Segments/Datagrams

  4. Session - Bits
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The OSI model defines PDUs for different layers: bits for Physical, frames for Data Link, packets for Network, and segments for Transport. The Session layer does not use bits as its PDU; bits are the PDU for the Physical layer.

Multiple choice

Which protocol would NOT use UDP?

  1. TFTP

  2. DNS

  3. DHCP

  4. SSH
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

SSH (Secure Shell) requires a reliable, connection-oriented transport to ensure data integrity and order, which is provided by TCP. TFTP, DNS, and DHCP are typically connectionless and use UDP.

Multiple choice

Which address is NOT an RFC 1918 address?

  1. 192.168.255.254

  2. 10.9.1.12

  3. 172.17.22.9

  4. 172.32.255.254
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

RFC 1918 defines private address ranges as 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. 172.32.x.x falls outside the 172.16.0.0/12 range (which ends at 172.31.255.255).

Multiple choice

Which address is an APIPA?

  1. 169.254.0.0/16

  2. 127.0.0.1

  3. 192.168.0.0/16

  4. 168.255.0.0/16
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

APIPA (Automatic Private IP Addressing) addresses are in the 169.254.0.0/16 range. This is used by clients when they cannot reach a DHCP server.

Multiple choice

Which ICMP response would NOT be sent when a packet is dropped by an ACL?

  1. Network administratively prohibited

  2. Host administratively prohibited

  3. Destination network unreachable

  4. Destination port unreachable
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When a packet is dropped by an ACL, the router typically sends an ICMP 'Administratively Prohibited' message. 'Destination network unreachable' is generally used for routing table issues, not ACL drops.

Multiple choice

What ICMP response will be sent when the TTL expires?

  1. Destination Unreachable

  2. Source Quench

  3. Redirect Message

  4. Time exceeded
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When an IPv4 packet's Time to Live (TTL) field reaches zero, the router discards the packet and sends an ICMP 'Time Exceeded' message back to the source.

Multiple choice

When would DNS use TCP?

  1. When DNS querys keep failing

  2. When conducting zone transfer

  3. Upon inital DNS connection request

  4. DNS cannot use TCP
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNS primarily uses UDP for queries. However, it switches to TCP for zone transfers (between servers) or when the response size exceeds the 512-byte UDP limit.

Multiple choice

What ports do FTP use to communicate?

  1. 20/21

  2. 21/22

  3. 22/23

  4. 23/25
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

FTP uses two ports: port 21 for the control connection (commands) and port 20 for the data connection.