CompTIA Server+ (SK0-005)TroubleshootingEasy
A server administrator is investigating a network issue where a newly deployed server can ping other devices on its local subnet but cannot reach resources on other subnets. The server is configured with a static IP address, subnet mask, and DNS servers. All other servers on the same subnet are communicating normally with external networks. Which of the following is the MOST likely cause of this issue?
- AFirewall blocking outbound traffic
- BIncorrect subnet mask
- CDNS server misconfiguration
- DIncorrect default gateway
Show answer & explanationAnswer & explanation
Correct answer: D. Incorrect default gateway
The ability to ping devices on the local subnet but not external networks strongly indicates a routing issue. The default gateway is responsible for directing traffic to other subnets, making an incorrect setting the most probable cause.
Why the other options are wrong
- A. While a firewall could block outbound traffic, the problem specifically mentions reaching *other subnets*, and other servers on the same subnet are working, suggesting a local server configuration issue rather than a general network firewall.
- B. An incorrect subnet mask would prevent communication even within the local subnet in many cases, or misidentify the local network range.
- C. DNS server misconfiguration would primarily affect name resolution (e.g., accessing websites by name), but pinging by IP address to other subnets would still work if routing was correct.
Default Gateway
A default gateway is the IP address of the router on a local network that acts as a forwarding host to other networks.
- Essential for communication outside the local subnet.
- Typically the router's IP address on the local segment.
- Misconfiguration leads to 'local only' connectivity.
Memory trick: Gateway is the door to the world beyond your block.