Routing Pt 3

Question 1

What does a router do when a packet reaches its destination network?

Answer 1

The router searches the routing table for a match.

Question 2

What action does a router take if the destination IP address matches a directly connected Ethernet interface?

Answer 2

The router searches the ARP table for the Layer 2 MAC address of the destination IP address.

Question 3

What happens if no ARP entry exists for a destination IP address?

Answer 3

The router sends an ARP request out of the Ethernet interface.

Question 4

What does the destination host send back in response to an ARP request?

Answer 4

An ARP reply containing its MAC address.

Question 5

In packet processing, what does the router do after receiving the MAC address from the ARP reply?

Answer 5

Encapsulates the packet in a new frame using the destination MAC address and the router’s source MAC address.

Question 6

What are common reasons for network failures?

Answer 6

An interface can fail, a service provider drops a connection, links can become oversaturated, an administrator may enter a wrong configuration.

Question 7

What is the responsibility of network administrators during network failures?

Answer 7

To pinpoint and solve the problem.

Question 8

What command is used to verify Layer 3 connectivity to a destination?

Answer 8

ping.

Question 9

What does the ‘traceroute’ command do?

Answer 9

Verifies the path to the destination network using ICMP echo reply messages.

Question 10

What information does ‘show ip route’ command display?

Answer 10

Displays the routing table, verifying route entries for destination IP addresses.

Question 11

What does ‘show ip interface brief’ command show?

Answer 11

Displays the status of device interfaces.

Question 12

What does the command ‘show cdp neighbors’ display?

Answer 12

Displays a list of directly connected Cisco devices.

Question 13

If connectivity from PC1 to PC3 fails, what should be checked first?

Answer 13

Extended pings from the R1 G0/0/0 interface to PC3.

Question 14

What was the outcome of the troubleshooting process when R2’s routing table revealed an incorrect static route?

Answer 14

The incorrect static route was removed, and a new static route was added.

Question 15

Fill in the blank: A host sends a packet to another host and sends it to the _______.

Answer 15

default gateway address.

Question 16

What does a router do if the destination IP address does not match a route table entry?

Answer 16

The router drops the packet and sends an ICMP message back to the source.

Question 17

When R3 receives a packet, what is the first action it takes?

Answer 17

Decapsulates the packet and searches the routing table for a match.

Question 18

What does R1 do if the destination IP address matches a static route entry?

Answer 18

Uses the static route to identify the next hop IP address or exit interface.

Question 19

What is the purpose of the ‘Gateway of last resort’ in a routing table?

Answer 19

To provide a default route when no specific route matches.

Question 20

True or False: A router will always drop a packet if it cannot find a matching route in the routing table.

Answer 20

True.

Question 21

What is the typical process for packet forwarding from R1 to R2?

Answer 21

R1 encapsulates the packet and forwards it out of interface S0/1/0 to R2.

Question 22

What happens when R2 receives a packet on its S0/1/0 interface?

Answer 22

It decapsulates and processes the packet similarly to R1.