Routing Pt 3 Flashcards
What does a router do when a packet reaches its destination network?
The router searches the routing table for a match.
What action does a router take if the destination IP address matches a directly connected Ethernet interface?
The router searches the ARP table for the Layer 2 MAC address of the destination IP address.
What happens if no ARP entry exists for a destination IP address?
The router sends an ARP request out of the Ethernet interface.
What does the destination host send back in response to an ARP request?
An ARP reply containing its MAC address.
In packet processing, what does the router do after receiving the MAC address from the ARP reply?
Encapsulates the packet in a new frame using the destination MAC address and the router’s source MAC address.
What are common reasons for network failures?
An interface can fail, a service provider drops a connection, links can become oversaturated, an administrator may enter a wrong configuration.
What is the responsibility of network administrators during network failures?
To pinpoint and solve the problem.
What command is used to verify Layer 3 connectivity to a destination?
ping.
What does the ‘traceroute’ command do?
Verifies the path to the destination network using ICMP echo reply messages.
What information does ‘show ip route’ command display?
Displays the routing table, verifying route entries for destination IP addresses.
What does ‘show ip interface brief’ command show?
Displays the status of device interfaces.
What does the command ‘show cdp neighbors’ display?
Displays a list of directly connected Cisco devices.
If connectivity from PC1 to PC3 fails, what should be checked first?
Extended pings from the R1 G0/0/0 interface to PC3.
What was the outcome of the troubleshooting process when R2’s routing table revealed an incorrect static route?
The incorrect static route was removed, and a new static route was added.
Fill in the blank: A host sends a packet to another host and sends it to the _______.
default gateway address.
What does a router do if the destination IP address does not match a route table entry?
The router drops the packet and sends an ICMP message back to the source.
When R3 receives a packet, what is the first action it takes?
Decapsulates the packet and searches the routing table for a match.
What does R1 do if the destination IP address matches a static route entry?
Uses the static route to identify the next hop IP address or exit interface.
What is the purpose of the ‘Gateway of last resort’ in a routing table?
To provide a default route when no specific route matches.
True or False: A router will always drop a packet if it cannot find a matching route in the routing table.
True.
What is the typical process for packet forwarding from R1 to R2?
R1 encapsulates the packet and forwards it out of interface S0/1/0 to R2.
What happens when R2 receives a packet on its S0/1/0 interface?
It decapsulates and processes the packet similarly to R1.
