SK0-003 · Question #866
A server administrator is checking connectivity on a mail server which appears to be working correctly. Testing by the administrator has shown that ping requests from the server are failing even…
The correct answer is D. Echo or echo reply is blocked by the firewall. The most likely reason for a mail server's mail services to function while ping requests fail is that a firewall is selectively blocking ICMP (ping) traffic.
Question
A server administrator is checking connectivity on a mail server which appears to be working correctly. Testing by the administrator has shown that ping requests from the server are failing even though mail is still working. Which of the following is the MOST likely cause of the failed ping requests?
Options
- AThe TCP/IP stack on the server is corrupted.
- BThe VLAN has been improperly configured.
- COne of the teamed NICs has failed on the server.
- DEcho or echo reply is blocked by the firewall.
How the community answered
(53 responses)- A4% (2)
- B9% (5)
- C4% (2)
- D83% (44)
Why each option
The most likely reason for a mail server's mail services to function while ping requests fail is that a firewall is selectively blocking ICMP (ping) traffic.
If the TCP/IP stack were corrupted, the server would be unable to perform any network communication, including sending and receiving mail.
An improperly configured VLAN would typically disrupt all network communication for the server, preventing mail services from functioning correctly.
In a NIC team, the failure of one NIC usually allows traffic to continue through the remaining active NICs, meaning both mail and ping should still work.
Firewalls are commonly configured to block ICMP Echo Request and Echo Reply messages (used by ping) to prevent network reconnaissance or specific denial-of-service attacks, while still permitting essential application traffic like email. This selective blocking explains why mail services continue to function despite ping failures.
Concept tested: Firewall rules and ICMP protocol filtering
Source: https://learn.microsoft.com/en-us/windows/security/threat-protection/windows-firewall/windows-firewall-with-advanced-security
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