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

The following commands were entered on a : Router(config)# access-list 2 deny 172.16.5.24 Router(config)# access-list 2 permit any The ACL is correctly applied to an interface. What can be concluded about the given set of commands?

  1. The wildcard mask 0.0.0.0 is assumed.

  2. The access list statements are misconfigured.

  3. All nodes on the 172.16.0.0 network will be denied access to other networks.

  4. No traffic will be allowed to access any nodes or services on the 172.16.0.0 network.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When creating a standard access list without specifying a wildcard mask, IOS assumes the wildcard mask 0.0.0.0, which matches only the exact host address specified. This is a host-specific ACL. The wildcard mask must be explicitly stated to match a range of addresses. Option B is incorrect because the commands are valid. Options C and D are incorrect because only the specific host 172.16.5.24 is denied, not the entire network.

Multiple choice

How does the application layer on a server usually process multiple client request for services?

  1. Ceases all connections to the service

  2. Denies multiple connections to a single daemon

  3. Suspends the current connection to allow the new connection

  4. Uses support from lower layer functions to distinguish between connections to the service
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The application layer relies on lower layers (especially the transport layer with TCP/UDP port numbers) to multiplex multiple connections to the same service. Port numbers allow the operating system to distinguish between different client connections to the same server daemon. The server does not cease connections, deny multiple connections (that would defeat the purpose of a server), or suspend current connections for new ones.

Multiple choice

Refer to the exhibit. Router1 is running IOS version 12.2. What will the network administrator need to do so that packets for unknown child routes of 172.16.0.0/24 will not be dropped?

  1. Issue the IP default-network command

  2. Use a classful routing protocol such as RIPv1

  3. Enable either OSPF or ISIS as the routing protocol

  4. Issue the IP classless command

  5. Do nothing, IP classless is on by default
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The 'ip classless' command enables classless routing behavior, allowing the router to forward packets destined for unknown subnets of a major network to the best available supernet or default route. Without this command, older IOS versions would drop packets for unknown child routes. In IOS 12.2, 'ip classless' was not the default behavior and had to be enabled manually for proper route forwarding.

Multiple choice

Refer to the exhibit. Hosts that are connected to switch SW1 are not able to communicate with hosts in the same VLAN that are connected to switch SW2. What should be done to fix the problem?

  1. Introduce a Layer 3 device in the topology.

  2. Configure both switches in VTP transparent mode to allow them to share VLAN information.

  3. Reconfigure the fa0/1 interface on switch SW1 with a static trunk configuration.

  4. Reconfigure the fa0/1 interface on switch SW1 with a static trunk configuration.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When hosts in the same VLAN on different switches cannot communicate, the issue is typically the trunk link between switches. Reconfiguring the interface with a static trunk configuration (rather than relying on DTP auto-negotiation) ensures the link becomes a trunk and carries all VLAN traffic. A Layer 3 device is not needed for same-VLAN communication. VTP transparent mode does not automatically create trunks.

Multiple choice

Refer to the exhibit. Server sends an ARP request for the MAC address of its default gateway. If STP is not enabled, what will be the result of this ARP request?

  1. Router_1 will drop the broadcast and reply with the MAC address of the next hop .

  2. Switch_A will reply with the MAC address of the Router_1 E0 interface.

  3. Switch_A and Switch_B will continuously flood the message onto the network.

  4. The message will cycle around the network until its TTL is exceeded.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When a server broadcasts an ARP request, switches flood the broadcast out all ports (except the incoming port). The router receives the broadcast and responds with its MAC address. The switch then forwards this unicast reply back to the server. Without STP, if there were loops, flooding could cause issues, but the correct answer is that the switch simply forwards the ARP response from the router.

Multiple choice

What is the proper order of the layers of the OSI model from the highest layer to the lowest layer?

  1. Physical, network, application, data link, presentation, session, transport

  2. Application, physical, session, transport, network, data link, presentation

  3. Application, presentation, physical, session, data link, transport, network

  4. Application, presentation, session, transport, network, data link, physical

  5. Presentation, data link, session, transport, network, physical, application
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The OSI model layers from highest (7) to lowest (1) are: Application (7), Presentation (6), Session (5), Transport (4), Network (3), Data Link (2), Physical (1). Layer 7 (Application) is closest to the user experience, while Layer 1 (Physical) deals with actual bit transmission over the medium. Memorizing 'All People Seem To Need Data Processing' helps recall the order from top to bottom.

Multiple choice

Which address provides an example of an IPv6 link-local address?

  1. FE80::1324:ABCD

  2. 2001:2345:AB12:1935::FEFF

  3. 2001:1234:0000:9CA::0876/64

  4. 1234:ABCD:5678:EF00:9234:AA22:5527:FC35
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

IPv6 link-local addresses always start with FE80::/10 prefix (FE80 to FEBF). They are automatically configured on every IPv6 interface and are used for communication on the local link only. The address FE80::1324:ABCD is a valid link-local address. Options B and C appear to be global unicast addresses (2001::/16). Option D is a full global unicast address without the link-local prefix.

Multiple choice

Which of the following statements are correct about RIP?

  1. It uses a broadcast to update all other routers in the network every 60 seconds.

  2. It uses a multicast address to update other routers every 90 seconds.

  3. It will send out an update if there is a failure of a link.

  4. It updates only contained information about routes that have changed since last update.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

RIP sends triggered updates immediately when a link failure occurs, which is option C. Option A is incorrect because RIP updates every 30 seconds (not 60) and uses broadcast, not multicast. Option B incorrectly states 90 seconds and multicast. Option D describes partial updates, which RIP does support, but the question focuses on update timing.

Multiple choice

Refer to the exhibit. A network administrator has to develop an IP addressing scheme that uses the 192.168.1.0 /24 address space. The network that contains the serial link has already been addressed out of a separate range. Each network will be allocated the same number of host addresses. Which network mask will be appropriate to address the remaining networks?

  1. 255.255.255.248

  2. 255.255.255.224

  3. 255.255.255.192

  4. 255.255.255.240

  5. 255.255.255.128
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice

Refer to the exhibit. Routers R1 and R2 are directly connected through a FastEthernet link but cannot form a neighbour adjacency. What could resolve the problem?

  1. The cost on R1 should be set higher.

  2. The priority on R1 should be set higher.

  3. The OSPF process ID numbers must match.

  4. A backup designated router needs to be added to the network.

  5. The hello and dead timers must be configured with the same values on both routers.
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice

Refer to the exhibit. PAT has been implemented on router R2. PC1 and PC2 are unsuccessful when attempting to connect to Internet resources. What is a possible cause?

  1. No NAT pool is configured.

  2. The inside and outside interfaces are switched.

  3. The access control list is configured with an incorrect access list number.

  4. The access control list is missing a statement for the 10.94.6.0 network.

  5. The IP NAT inside source list 1 interface command is pointing to the wrong serial interface.
Reveal answer Fill a bubble to check yourself
B Correct answer