200-301 Question 298
Single answerA router receives a packet with a destination IP address of 192.168.1.73. The router's routing table contains the following entries:
- 192.168.1.0/24 via GigabitEthernet0/0
- 192.168.1.64/26 via GigabitEthernet0/1
- 192.168.0.0/16 via GigabitEthernet0/2
- 0.0.0.0/0 via GigabitEthernet0/3
Which interface will the router forward the packet to?
- A
GigabitEthernet0/0
- B
GigabitEthernet0/1
- C
GigabitEthernet0/2
- D
GigabitEthernet0/3
Show answer and explanation
Correct answer: B
Explanation
The router uses the longest prefix match rule to determine the most specific route to forward a packet. In this case, the destination IP address 192.168.1.73 matches three entries: 192.168.1.0/24, 192.168.1.64/26, and 192.168.0.0/16. The /26 prefix is the longest and therefore the most specific, so the router forwards the packet via GigabitEthernet0/1.
- A. Incorrect.
GigabitEthernet0/0 is associated with the 192.168.1.0/24 route, but it is not the most specific match due to a shorter prefix length (24).
- B. Correct.
GigabitEthernet0/1 is associated with the 192.168.1.64/26 route, which is the most specific match for the 192.168.1.73 destination address, as it has the longest prefix length (26).
- C. Incorrect.
GigabitEthernet0/2 is associated with the 192.168.0.0/16 route, but it is not the most specific match due to a shorter prefix length (16).
- D. Incorrect.
GigabitEthernet0/3 is associated with the default route (0.0.0.0/0), which is only used when no other matches are found.