CompTIA Server+ (SK0-005)TroubleshootingMedium
A server administrator discovers that a critical application on a Windows server is intermittently failing to connect to its database, which resides on a different server. Pinging the database server by IP address is successful, but pinging by hostname sometimes fails. Other services on the application server can resolve external hostnames without issue. Which of the following is the MOST likely cause of this problem?
- AThe application server's network adapter is faulty.
- BThere is an issue with the application server's DNS client configuration.
- CThe database server is experiencing high CPU utilization.
- DThe database server's firewall is blocking connections.
Show answer & explanationAnswer & explanation
Correct answer: B. There is an issue with the application server's DNS client configuration.
The ability to ping by IP but not consistently by hostname points directly to a name resolution issue. Since other services can resolve external hostnames, the problem is likely specific to how this application or the server's DNS client is configured for internal name resolution.
Why the other options are wrong
- A. If the network adapter were faulty, pinging by IP address would also be unreliable or fail entirely.
- C. High CPU utilization on the database server might cause connection timeouts or slow responses, but it would not prevent hostname resolution on the application server itself.
- D. If the firewall were blocking connections, pinging by IP would also likely fail for the application, and the problem description points to name resolution, not connectivity.
DNS Client Misconfiguration
Incorrect settings on a client machine that prevent it from properly resolving hostnames to IP addresses, often leading to connectivity issues when using hostnames.
- Symptoms include successful IP-based connectivity but failed hostname-based connectivity.
- Can be caused by incorrect DNS server addresses, firewall rules blocking DNS traffic, or issues with local host files.
- Troubleshooting involves checking `ipconfig /all` (Windows) or `cat /etc/resolv.conf` (Linux) and testing DNS servers.
Memory trick: Don't Name Servers, Just Say IP!