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. 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 controls which protocols are allowed for VTY connections. If it only specifies SSH (transport input ssh), Telnet will be denied. The command must include SSH or all to permit Telnet access. This is a common misconfiguration when enabling SSH.

Multiple choice

Which of the following frame relay flow control mechanisms is used to signal routers that they should reduce the flow rate of frames?

  1. DE

  2. BE

  3. CIR

  4. FECN

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

FECN (Forward Explicit Congestion Notification) is a Frame Relay mechanism set by the network to signal congestion. When a frame experiences congestion, the network marks it with FECN, and the destination device can then use BECN (Backward Explicit Congestion Notification) to signal the source to reduce its transmission rate. DE (Discard Eligibility) is used to mark low-priority frames that can be dropped during congestion, while CIR (Committed Information Rate) is the guaranteed bandwidth. BECN signals the source directly about congestion.

Multiple choice

Which of the following statements correctly describes a feature of RIP?

  1. RIP is a link-state routing protocol.

  2. RIP uses only one metric hop count for path selection.

  3. Advertised routes with hop counts greater than 10 are unreachable.

  4. Messages are broadcast every 10 seconds.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

RIP is a distance-vector routing protocol that uses hop count as its sole metric for path selection. The maximum hop count is 15, with 16 considered unreachable (not 10 as option C suggests). RIP version 1 broadcasts updates every 30 seconds to address 255.255.255.255, while RIP version 2 uses multicast 224.0.0.9. RIP does not use bandwidth, delay, reliability, or load in its routing decisions, making it simple but limited in complex networks.

Multiple choice

Your supervisor has asked you to setup an access list that will filter on source addresses only. Which of the following access lists filter on the source address only?

  1. Standard access list

  2. Extended access list

  3. Dynamic access list

  4. Named access list
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Standard access list filters by source address. This is as basic filtering form as it gets. If a standard ACL is applied, the switch router compares the source IP address with the ACL.

Multiple choice

You are troubleshooting a problem with SNMP. At what layer of the OSI model does SNMP operate?

  1. Transport

  2. Application

  3. Network

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

An application that communicates with other computers is implementing OSI application layer concepts. The application layer refers to communications services to applications. For example, a word processor that lacks communications capabilities would not implement code for communications, and word processor programmers would not be concerned about OSI Layer 7. However, if an option for transferring a file were added, the word processor would need to implement OSI Layer 7 (or the equivalent layer in another protocol specification).

Multiple choice

A switch operating STP has just been powered up. You know it will run through various port states before becoming a fully functional switch. What is the correct order of port states that a switch running STP will transition though from initialization?

  1. Blocking, listening, learning, forwarding, disabled

  2. Listening, learning, disabled, forwarding, blocking

  3. Learning, disabled, forwarding, blocking, listening

  4. Forwarding, disabled, blocking, listening, learning
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A Switch with STP enabled on its Layer 2 interface moves through these five states as follows:

  • From initialization to blocking 
  • From blocking to listening or to disabled 
  • From listening to learning or to disabled 
  • From learning to forwarding or to disabled 
  • From forwarding to disabled
Multiple choice

A network administrator needs to allow traffic through the firewall router for sessions that originate from within the company network, but the administrator must block traffic for sessions that originate outside the network of the company. What type of ACL is most appropriate?

  1. dynamic

  2. port-based

  3. reflexive

  4. time-based
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Reflexive ACLs filter IP traffic based on session state - they allow outbound traffic from internal hosts and dynamically create temporary inbound rules to allow the return traffic. This permits sessions originating from inside the network while blocking external-initiated connections. Dynamic ACLs (option A) require user authentication, port-based ACLs (option B) filter by port numbers, and time-based ACLs (option D) activate based on time schedules. Reflexive ACLs are designed specifically for this outbound-initiated traffic scenario.

Multiple choice

Two routers Rtr1 and Rtr2 are both configured with RIP only. What will be the result when Rtr1 receives a routing update that contains a higher cost path to a network already in its routing table?

  1. The update information will replace the existing routing table entry.

  2. The update information will be added to the existing routing table.

  3. The existing routing table entry will be deleted from the routing table and all routers will exchange routing updates to reach convergence.

  4. The update will be ignored and no further action will be taken.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

RIP uses hop count as its metric, and when a router receives a routing update containing a higher cost path to a network already in its routing table, it ignores that update. RIP only installs better (lower hop count) paths. The existing routing table entry remains unchanged because RIP routers do not accept inferior routes - this is fundamental to distance vector behavior where only optimal paths are maintained.

Multiple choice

What PPP protocol provides dynamic addressing, authentication, and multilink?

  1. HDLC

  2. LCP

  3. NCP

  4. X.25
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

LCP (Link Control Protocol) is the correct PPP protocol that establishes, configures, maintains, and terminates the link connection. LCP handles authentication (via PAP or CHAP), negotiates parameters like MRU and magic number, and supports multilink PPP. NCP (Network Control Protocol) handles network layer protocol configuration like IP assignment, but LCP is responsible for the broader link management functions listed. HDLC is a proprietary Cisco protocol, not PPP, and X.25 is an older WAN protocol.

Multiple choice

Which command would the network administrator issue to determine if load balancing is in effect on a router?

  1. show ip protocols

  2. show ip route

  3. show ip interface brief

  4. show ip interface
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The show ip route command displays the routing table where you can see multiple equal-cost paths to the same destination, which indicates load balancing is active. When load balancing is implemented, the routing table shows multiple next-hop addresses for the same network prefix. Show ip protocols shows routing protocol parameters, and show ip interface commands display interface status but not load balancing state.