100-150 Question 227
Single answerA user reports that they cannot reach a specific website. You run a series of network diagnostic commands from their computer. The ping command to the website's IP address times out, the tracert command shows a timeout after reaching a specific hop, and the nslookup command successfully resolves the website's domain name to an IP address. What could be the most likely reason for this issue?
- A
The website's DNS server is misconfigured.
- B
A firewall is blocking ICMP traffic.
- C
The user's computer is not connected to the network.
- D
The website's IP address is incorrect.
Show answer and explanation
Correct answer: B
Explanation
The ping and tracert commands rely on ICMP packets to function, and if a firewall along the network path blocks ICMP traffic, these commands will fail. However, nslookup does not use ICMP and instead queries DNS servers directly, which is why it succeeds. This makes a firewall blocking ICMP traffic the most likely cause of the issue.
- A. Incorrect.
The
nslookupcommand successfully resolving the domain name indicates that DNS is functioning correctly, so a misconfigured DNS server is unlikely. - B. Correct.
A firewall blocking ICMP traffic would explain why the
pingandtracertcommands fail, as both rely on ICMP packets for their functionality. - C. Incorrect.
If the user's computer was not connected to the network, none of the commands would work, including
nslookup, which successfully resolved the domain name. - D. Incorrect.
Since
nslookupsuccessfully resolved the domain name to the correct IP address, it is unlikely that the IP address is incorrect.