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

When connectionless protocols are implemented at the lower layers of the OSI model, what is usually used to acknowledge that the data was received and to request the retransmission of missing data?

  1. IP

  2. UDP

  3. Ethernet

  4. A connectionless acknowledgement

  5. An upper-layer, connection-oriented protocol or service
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Connectionless protocols at lower OSI layers (like IP at Layer 3 or Ethernet at Layer 2) do not provide acknowledgment or retransmission services. When data reliability is needed, upper-layer connection-oriented protocols or services (typically TCP at Layer 4) provide acknowledgments and request retransmission of missing data. IP itself is connectionless and unreliable - it relies on upper layers for reliability. The option 'connectionless acknowledgement' is contradictory because connectionless protocols don't provide acknowledgments.

Multiple choice

Refer to the exhibit. All routers are running RIP version 2. JAX is configured to just advertise the 10.0.0.0/24 network. CHI is configured to advertise the 172.16.0.0/16 network. A network administrator enters the commands shown in the exhibit. What changes will occur in this network?

  1. The JAX router will ignore updates for the 172.16.0.0/16 network due to split horizon issues.

  2. The CHI router will install a route to the 192.168.0.0/16 network in its routing table.

  3. The routing table for CHI will have the 192.168.0.0/16 route but it will have an S next to the route.

  4. The ORL router will apply a 255.255.0.0 subnet mask to all networks in the routing updates it forwards.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When 'no network 172.16.0.0' is configured on JAX, it stops advertising 172.16.0.0/16 to ORL. However, CHI can still receive 172.16.0.0/16 from other sources and advertise it. When ORL receives 192.168.0.0/16 from JAX (after JAX receives it via distribute-list), ORL will advertise it to CHI. CHI will install this route in its routing table with a 'R' tag (RIP), not 'S' (static). The distribute-list controls what routes JAX advertises to ORL, but doesn't prevent ORL from advertising learned routes to CHI.

Multiple choice

What technology is used to dynamically map next hop, network layer addresses to virtual circuits in a frame relay network?

  1. Inverse ARP

  2. LMI

  3. DLCI

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

Inverse ARP dynamically learns the network layer address of the remote device associated with a DLCI. This eliminates manual configuration of Frame Relay mappings. LMI is the signaling protocol, DLCI identifies virtual circuits, and FECN indicates congestion.

Multiple choice

Refer to the exhibit. Which of the following options correctly identifies content that the frame data field may contain?

  1. Network layer packet

  2. Physical addressing

  3. FCS and SOF

  4. Preamble and stop frame
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The frame data field (payload) carries the encapsulated network layer PDU (packet). Physical addressing (MAC addresses) goes in the header, not data field. FCS (Frame Check Sequence) is a trailer field. SOF (Start of Frame) and preamble are preamble fields.

Multiple choice

What will be the result of adding the command ip dhcp excluded-address 192.168.24.1 192.168.24.5 to the configuration of a local router that has been configured as a DHCP server?

  1. Traffic that is destined for 192.168.24.1 and 192.168.24.5 will be dropped by the router.

  2. Traffic will not be routed from clients with addresses between 192.168.24.1 and 192.168.24.5.

  3. The DHCP server will not issue the addresses ranging from 192.168.24.1 to 192.168.24.5.

  4. The router will ignore all traffic that comes from the DHCP servers with addresses 192.168.24.1 and 192.168.24.5.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The 'ip dhcp excluded-address' command tells the DHCP server to exclude a range of addresses from being assigned to clients. This is typically done for servers, printers, or router interfaces that need static IP addresses. It does not affect traffic routing or dropping.

Multiple choice

Refer to the exhibit. A network administrator has issued the commands that are shown on Router1 and Router2. A later review of the routing tables reveals that neither router is learning the LAN network of the neighbor router. What is most likely the problem with the RIPng configuration?

  1. The serial interfaces are in different subnets.

  2. The RIPng process is not enabled on interfaces.

  3. The RIPng network command is not configured.

  4. The RIPng processes do not match between Router1 and Router2.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In RIPng, you must enable the RIPng process on specific interfaces using 'ipv6 rip enable'. Simply creating the RIPng process is not enough. The network command is not used in RIPng (that's RIPv2). Interface mismatch is possible but less likely than missing enable command.

Multiple choice

An engineer creates a static route by entering the Router(config)# ip route 10.0.0.0 255.255.255.0 192.168.1.2 command. What can be concluded about this route?

  1. The administrative distance of this route is 1.

  2. 192.168.1.2 is the address of an interface on this router.

  3. This route will display as a directly connected network in the routing table.

  4. Packets with a destination IP address of 192.168.1.2 will be forwarded to the 10.0.0.0/24 network first.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A static route configured as 'ip route ' without an explicit administrative distance defaults to AD=1. This is the most trusted static route. 192.168.1.2 is the next-hop (gateway), not a local interface. The route appears as 'S' (static) in routing table, not directly connected (C).

Multiple choice

A PC cannot connect to any remote websites, ping its default gateway, or ping a printer that is functioning properly on the local network segment. Which action will verify that the TCP/IP stack is functioning correctly on this PC?

  1. Use the ipconfig /all command at the host's command prompt.

  2. Use the ping 127.0.0.1 command at the command prompt.

  3. Use the traceroute command at the command prompt to identify any failures on the path to the gateway.

  4. Use FTP to check for connectivity to remote sites.

  5. Download a troubleshooting tool from the PC manufacturer's website.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Pinging 127.0.0.1 (localhost loopback) verifies that the TCP/IP stack is functioning on the local PC. If this ping succeeds, the TCP/IP protocol stack is working properly. If it fails, the stack is corrupted and needs to be reinstalled. ipconfig only shows configuration, traceroute won't work if local stack is broken, and FTP tests connectivity not the stack itself.

Multiple choice

When must a router serial interface be configured with the clock rate command?

  1. When the interface is functioning as a DTE device.

  2. When the interface timers have been cleared.

  3. When the connected DTE device is shut down.

  4. When the interface is functioning as a DCE device.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The clock rate command is required on a serial interface when it is functioning as a DCE (Data Communications Equipment). The DCE device provides the clocking signal for synchronous serial communication. DTE (Data Terminal Equipment) devices receive clocking from the DCE and do not need the clock rate command.

Multiple choice

Refer to the exhibit. While trying to diagnose a routing problem in the network, the network administrator runs the debug ip rip command. What can be determined from the output of this command?

  1. The router will be unable to ping 192.168.1.2.

  2. The router has two interfaces that participate in the RIP process.

  3. The router will forward the updates for 192.168.1.0 on interface Serial0/0/1.

  4. The router is not originating routes for 172.16.1.0.
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice

Refer to the exhibit. Partial results of the show access-lists and show ip interface FastEthernet 0/1 commands for router Router1 are shown. There are no other ACLs in effect. Host A is unable to telnet to host B. Which of the following actions will correct the problem but still restrict other traffic between the two networks?

  1. Apply the ACL in the inbound direction.

  2. Apply the ACL on the FastEthernet 0/0 interface.

  3. Reverse the order of the TCP protocol statements in the ACL.

  4. Modify the second entry in the list to permit tcp host 172.16.10.10 any eq telnet.
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice

Refer to the exhibit. A technician is teaching a trainee to interpret the results of various frame relay troubleshooting commands. What conclusion can be drawn from the output that is shown?

  1. Neighbouring routers should use DLCI 177 to reach the branch router.

  2. DLCI 177 will be used to identify all broadcasts that are sent out the branch router.

  3. The branch router has the address 192.168.3.1 configured for the S0/0/0 interface.

  4. To reach 192.168.3.1, the branch router will use the virtual circuit that is identified by DLCI 177.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In Frame Relay, DLCI (Data Link Connection Identifier) identifies the virtual circuit used to reach a specific IP address. The output shows that to reach the destination 192.168.3.1, the router will use the virtual circuit identified by DLCI 177. This is the standard mapping shown in Frame Relay maps.