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

RIPv2 is the configured routing protocol on the routers in a network. The command Router(config-router)# no version 2 is entered on the routers. What effect does entering this command have on routing updates?

  1. Subnet masks will be added to the routing updates.

  2. Routing updates will be sent out using multicast address 224.0.0.9.

  3. Version 1 and 2 updates will be received and the version 2 updates will not be sent.

  4. The RIP routing process will be removed from the router and routing updates will not be forwarded.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When the no version 2 command is used in RIP configuration, the router stops sending RIPv2 updates but still receives both RIPv1 and RIPv2 updates. This allows compatibility with mixed-version networks during migration. The router doesn't add subnet masks (RIPv1 doesn't support them), doesn't use multicast (RIPv1 uses broadcast 255.255.255.255), and doesn't remove RIP entirely - it just changes the transmission behavior to version 1 while remaining backward-compatible for receiving.

Multiple choice

Refer to the exhibit. How does SW1 manage traffic coming from Host A?

  1. SW1 drops the traffic because it is untagged.

  2. SW1 leaves the traffic untagged and forwards it over the trunk.

  3. SW1 tags the traffic with the lowest VLAN ID value and forwards it over the trunk link.

  4. SW1 encapsulates the traffic with 802.1Q encapsulation and forwards it over the trunk link.
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice

Which protocol is used to look up an IP address from a known Ethernet address?

  1. TCP

  2. RARP

  3. ARP

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

RARP (Reverse Address Resolution Protocol) is used to obtain an IP address when the MAC address is known. This is the reverse of ARP, which resolves MAC addresses from known IP addresses. RARP was historically used by diskless workstations to obtain their IP configuration at boot. TCP handles transport, IP handles routing, and ARP resolves MAC from IP - none of these look up IP from Ethernet addresses like RARP does.

Multiple choice

What is a PDU?

  1. corruption of a frame during transmission

  2. data reassembled at the destination

  3. retransmitted packets due to lost communication

  4. a layer specific encapsulation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A PDU (Protocol Data Unit) is the technical term for a layer-specific encapsulation unit as data moves down the OSI or TCP/IP stack. At each layer, data is encapsulated with that layer's header (and trailer) creating a PDU - bits at Physical, frames at Data Link, packets at Network, segments at Transport, and data at Application layers. The other options describe transmission problems or processes, not what a PDU fundamentally is.

Multiple choice

Refer to the exhibit. ACL 120 is configured inbound on the serial0/0/0 interface on router R1, but the hosts on network 172.11.10.0/24 are able to telnet to network 10.10.0.0/16. On the basis of the provided configuration, what should be done to remedy the problem?

  1. Apply the ACL outbound on the serial0/0/0 interface on router R1.

  2. Apply the ACL outbound on the FastEthernet0/0 interface on router R1.

  3. Include the established keyword at the end of the first line in the ACL.

  4. Include a statement in the ACL to deny the UDP traffic that originates from 172.11.10.0/24 network.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

ACLs applied inbound on an interface filter traffic entering that interface. Since hosts on 172.11.10.0/24 can still telnet to 10.10.0.0/16, the traffic isn't passing through the serial0/0/0 interface where the ACL is applied inbound. Applying the ACL outbound (on serial0/0/0) would filter traffic leaving R1 toward the 172.11.10.0 network. Applying it on FastEthernet0/0 (B) would be incorrect since that's a different interface.

Multiple choice

Select the correct combination of Routing Protocol and Routing Protocol type.

  1. RIP -- Distance Vector

  2. RIP -- Link-State

  3. OSPF -- Distance Vector

  4. OSPF -- Link-State
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

RIP (Routing Information Protocol) is a Distance Vector routing protocol that uses hop count as its metric. OSPF (Open Shortest Path First) is a Link-State protocol that uses Dijkstra's algorithm. Option A correctly pairs RIP with Distance Vector. Option B is wrong because RIP is not Link-State. Option C is wrong because OSPF is not Distance Vector. Option D has the correct protocol-type pairing but A is the answer that's marked correct.

Multiple choice

What is the result when the command permit tcp 10.25.132.0 0.0.0.255 any eq smtp is added to a named access control list and applied on the inbound interface of a router?

  1. TCP traffic with a destination to the 10.25.132.0/24 is permitted.

  2. Only Telnet traffic is permitted to the 10.24.132.0/24 network

  3. Ttraffic from 10.25.132.0/24 is permitted to anywhere on using any port.

  4. Traffic using port 25 from the 10.25.132.0/24 is permitted to all destinations.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The ACL command 'permit tcp 10.25.132.0 0.0.0.255 any eq smtp' permits TCP traffic from source network 10.25.132.0/24 (wildcard mask 0.0.0.255) to any destination, but only for port 25 (SMTP). Option A is wrong because it reverses source/destination. Option B is wrong because it specifies Telnet (port 23) and the wrong network. Option C is wrong because it claims 'any port' when only SMTP (25) is permitted. Option D correctly identifies that traffic from 10.25.132.0/24 using port 25 can go to any destination.

Multiple choice

A network administrator is using an application that is monitoring packets on the network and sees an EIGRP update packet. What is the purpose of the update packet?

  1. The packet is sent to discover neighbors within the EIGRP network.

  2. The packet is sent to search for network devices within an EIGRP network.

  3. The packet is used to propagate routing information within the EIGRP network.

  4. The packet is used to send an unreachable reply to another router within the EIGRP network.

  5. The packet is used to notify all routers that EIRGP has failed on one of the routers within the EIGRP network.
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice

Which of the following statements describes the use of voice VLANs in Cisco IP telephony?

  1. The voice VLAN carries both tagged and untagged traffic.

  2. The voice VLAN carries untagged traffic having special QoS markings.

  3. The voice VLAN must be configured on the switch port to which the IP phone attaches.

  4. Data and voice frames are tagged with same VLAN ID between the IP phone and the switch when a voice VLAN is configured.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In Cisco IP telephony, voice VLANs must be configured on the switch port connected to the IP phone. The IP phone tags voice traffic with the voice VLAN ID while data traffic passes through untagged or with a data VLAN. Option A is wrong because voice VLAN carries only tagged voice traffic. Option B is wrong because voice VLAN carries tagged traffic, not untagged. Option D is wrong because voice and data use different VLAN IDs. Option C correctly states that the voice VLAN must be configured on the switch port.

Multiple choice

Refer to the exhibit. What path will packets from the 192.168.1.0/24 network travel to reach the 10.0.0.0/8 network if RIP is the active routing protocol?

  1. The path will be router A -> router B -> router C -> router E.

  2. The path will be router A -> router D -> router E

  3. Router A will load balance between the router A -> router D -> router E and router A -> router B -> router C -> router E path

  4. Packets will alternate paths depending on the order they arrive at router A.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

RIP uses hop count as its metric and has a maximum of 15 hops (16 is unreachable). Looking at the paths: Path A-B-C-E has 3 hops (A->B, B->C, C->E). Path A-D-E has only 2 hops (A->D, D->E). RIP will choose the path with the lowest hop count, so it will use A->D->E. Option A is wrong because it has more hops. Option C is wrong because RIP doesn't load balance by default across unequal-cost paths. Option D is wrong because RIP doesn't alternate paths based on packet order.

Multiple choice

Refer to the exhibit. B receives a packet with a destination address of 10.16.1.97. What will router B do?

  1. drop the packet

  2. forward the packet via the route to 10.16.1.0

  3. forward the packet via the route to 10.16.1.64

  4. use the default route
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Router B will use its default route when no more specific route matches the destination. The packet's destination address 10.16.1.97 does not match any specific route in the routing table (likely only has the route to 10.16.1.64/26 and a default route). With ip classless behavior, the router uses the default route rather than dropping the packet.

Multiple choice

What determines if the router implements a classless route lookup process?

  1. Child routes are present in the routing table.

  2. A classless routing protocol has been configured on the router.

  3. The command ip classless is enabled on the router.

  4. Multiple routes with different masks to the same destination are in the routing table.

  5. Routing table entries have a next-hop IP address and an exit interface for each child route.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A router implements classless route lookup when a classless routing protocol is configured. RIPv2, EIGRP, OSPF, and IS-IS are classless protocols that include subnet mask information in routing updates. The ip classless command controls forwarding behavior but doesn't determine the routing protocol's classless nature.