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

Refer to the exhibit. Router R2 is configured properly and all interfaces are functional. Router R1 has been installed recently. Host A is unable to ping host B. Which procedure can resolve this problem?

  1. Configure a static route on R1 using the IP address of the serial interface on R1.

  2. Configure a default route on R1 with the exit interface Fa0/0 on R1.

  3. Configure a static route on R1 using the IP address of S0/0/0 on R2.

  4. Configure a default route on R1 using the IP address of Fa0/0 on R2.
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice

Which of the following events occurs during the transport layer three-way handshake?

  1. The two applications exchange data.

  2. TCP initializes the sequence numbers for the sessions.

  3. UDP establishes the maximum number of bytes to be sent.

  4. The server acknowledges the bytes of data received from the client.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The TCP three-way handshake (SYN, SYN-ACK, ACK) serves to establish connection parameters and synchronize sequence numbers between the two endpoints. The initial sequence numbers (ISNs) are exchanged during this handshake. Data exchange occurs after the handshake completes. UDP does not use a handshake. The server acknowledges data during the data transfer phase, not during the handshake.

Multiple choice

Refer to the exhibit. Frame Relay connectivity has been configured in the network and OSPF is used as the routing protocol. Router R1 can successfully ping the router R2 serial interface. When R1 attempts to ping network 192.168.3.0/24 the ping fails. What additional configuration should be applied on all routers to remedy the problem?

  1. Add the broadcast keyword in the Frame Relay map command on both routers.

  2. Issue the frame-relay interface-dlci command in addition to the frame-relay map command on both router interfaces.

  3. Remove the frame-relay map command and replace with the frame-relay interface-dlci command on both router interfaces.

  4. Apply the no frame-relay inverse-arp command on both router interfaces.
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice

When NAT is in use, what is used to determine the addresses that can be translated on a Cisco router?

  1. Access control list

  2. Routing protocol

  3. Inbound interface

  4. ARP cache
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

On Cisco routers, Network Address Translation (NAT) uses Access Control Lists (ACLs) to define which IP addresses are eligible for translation. The ACL acts as a match criterion that specifies the 'inside local' addresses that should be translated to 'inside global' addresses. Routing protocols, interfaces, and ARP cache are not used for this purpose.

Multiple choice

Refer to the exhibit. The corporate network that is shown has been assigned network 172.16.128.0/19 for use at branch office LANs. If VLSM is used, what mask should be used for addressing hosts at Branch4 with minimal waste from unused addresses?

  1. /19

  2. /20

  3. /21

  4. /22

  5. /23
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

For a /19 network (172.16.128.0 to 172.16.159.255), we need to address 500+ hosts efficiently. A /22 provides 1022 usable addresses (2^10-2), which is sufficient with minimal waste. Smaller masks (/19-/21) waste addresses; /23 only gives 510 hosts, which is insufficient. Branch4 likely needs 500-1000 hosts.

Multiple choice

Where should a standard access control list be placed?

  1. Close to the source

  2. Close to the destination

  3. On an Ethernet port

  4. On a serial port
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Standard access control lists should be placed close to the destination, not the source. This is because standard ACLs only filter based on source IP and cannot distinguish between permitted and denied traffic streams. Placing them near the source might block legitimate traffic destined for other networks.

Multiple choice

During a TCP communication session, if the packets arrive to the destination out of order, what will happen to the original message?

  1. The packets will not be delivered.

  2. The packets will be retransmitted from the source.

  3. The packets will be delivered and reassembled at the destination.

  4. The packets will be delivered and not reassembled at the destination.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

TCP provides reliable, ordered delivery through sequence numbers in every segment. When packets arrive out of order, the receiving TCP buffer stores them until missing segments arrive, then reassembles everything into the original message. This reassembly happens automatically at the destination before data is delivered to the application.

Multiple choice

Refer to the exhibit. The configuration steps that are listed in the exhibit have been entered in switch S1 via the console. Subsequent attempts to telnet to the switch are not successful. What is causing the problem?

  1. The switch must be configured with SSH version 1.

  2. The transport input command must specify Telnet access.

  3. The RSA keys must be returned to zero before SSH will permit Telnet access.

  4. The IP domain-name command must also be entered in line configuration mode for the VTY lines.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The transport input command on VTY lines controls which protocols are allowed for remote access. If it is set to only SSH (as implied by the SSH configuration), Telnet will be blocked. To permit both SSH and Telnet, the command must explicitly allow both protocols with transport input ssh telnet.

Multiple choice

What is the result when the command permit tcp 192.168.4.0 0.0.3.255 any eq telnet is entered in an access control list and applied on the inbound interface of a router?

  1. All traffic that originates from 192.168.4.0/24 is permitted.

  2. All TCP traffic is permitted and all other traffic is denied.

  3. All Telnet traffic from the 192.168.0.0/16 network is permitted.

  4. All traffic from the 192.168.4.0/22 network is permitted on TCP port 23.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The wildcard mask 0.0.3.255 corresponds to a /22 subnet mask (255.255.252.0), which covers the address range 192.168.4.0 through 192.168.7.255. Combined with eq telnet (TCP port 23), this ACL permits only Telnet traffic originating from anywhere in this /22 network to any destination.

Multiple choice

A router has learned two equal cost paths to a remote network via the EIGRP and RIP protocols. Both protocols are using their default configurations. Which path to the remote network will be installed in the routing table?

  1. the path learned via EIGRP

  2. the path learned via RIP

  3. the path with the highest metric value

  4. both paths with load balancing
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When multiple routing protocols learn paths to the same destination, the router chooses the path with the lowest administrative distance. EIGRP has an administrative distance of 90, while RIP has 120. Therefore, even with equal costs, the EIGRP path is preferred and installed in the routing table.

Multiple choice

Refer to the exhibit. The Ethernet interface on Router2 goes down and the administrator notices that the route is still valid in the routing table of Router1. How much longer will it take for Router1 to mark the route invalid by setting the metric to 16?

  1. 30 seconds

  2. 90 seconds

  3. 155 seconds

  4. 180 seconds

  5. 255 seconds
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

RIP uses a 180-second invalid timer. If a route is not refreshed (no update received) within 180 seconds, it is marked invalid and the metric is set to 16 (unreachable). This is followed by a 240-second flush timer before the route is completely removed from the routing table.

Multiple choice

Refer to the exhibit. A network technician is trying to determine the correct IP address configuration for Host A. What is a valid configuration for Host A?

  1. IP address: 192.168.100.19; Subnet Mask: 255.255.255.248; Default Gateway: 192.16.1.2

  2. IP address: 192.168.100.20; Subnet Mask: 255.255.255.240; Default Gateway: 192.168.100.17

  3. IP address: 192.168.100.21; Subnet Mask: 255.255.255.248; Default Gateway: 192.168.100.18

  4. IP address: 192.168.100.22; Subnet Mask: 255.255.255.240; Default Gateway: 10.1.1.5

  5. IP address: 192.168.100.30; Subnet Mask: 255.255.255.240; Default Gateway: 192.168.1.1
Reveal answer Fill a bubble to check yourself
B Correct answer