200-301 Question 261
Single answerA network administrator is troubleshooting a connectivity issue between two routers, R1 and R2, which are connected via a serial link. R1's interface is configured with an IP address of 192.168.1.1/30, and R2's interface is configured with 192.168.1.2/30. The administrator can successfully ping R1's local interface from R2, but pings to a remote server (8.8.8.8) fail from both routers. What could be the most likely cause of this issue?
- A
The subnet mask on R1 and R2 is misconfigured.
- B
A static route to the remote network is missing on both R1 and R2.
- C
The serial link between R1 and R2 is down.
- D
The default gateway on R1 and R2 is not set.
Show answer and explanation
Correct answer: B
Explanation
The issue described points to a routing problem. Since the local connectivity between R1 and R2 is confirmed to be working, the inability to reach a remote server like 8.8.8.8 indicates that neither router has the necessary route to forward packets to that destination. This can be resolved by adding a static route or configuring a dynamic routing protocol between the routers.
- A. Incorrect.
The subnet mask on R1 and R2 is correctly configured as /30, which allows for two usable IP addresses. This is not the issue.
- B. Correct.
When pings to a remote server fail despite local connectivity being functional, the most common cause is a missing static route or routing configuration. R1 and R2 likely lack a route to reach the remote network (8.8.8.8).
- C. Incorrect.
The serial link between R1 and R2 is up since pings between their local interfaces are successful. This is not the problem.
- D. Incorrect.
Default gateway settings are not applicable here, as routers use routing tables to forward packets. The issue lies with a missing route, not a missing default gateway.