CompTIA Network+ (N10-009)Network TroubleshootingEasy
A network technician is troubleshooting a client workstation that can access internal network resources by IP address but cannot resolve public website names. Pinging external IP addresses works successfully. What is the MOST likely cause of this issue?
- AIncorrect subnet mask configuration.
- BFaulty network interface card (NIC).
- CBlocked outbound firewall rule.
- DIncorrect DNS server configuration.
Show answer & explanationAnswer & explanation
Correct answer: D. Incorrect DNS server configuration.
The ability to reach internal resources by IP and external IP addresses indicates that basic network connectivity and routing are functional. The failure to resolve public website names points directly to a problem with DNS resolution.
Why the other options are wrong
- A. An incorrect subnet mask would likely prevent access to both internal and external resources, even by IP.
- B. A faulty NIC would prevent any network connectivity, not just name resolution.
- C. A blocked outbound firewall rule would prevent access to external IP addresses, which the problem states is working.
DNS Resolution Failure
Occurs when a client cannot translate a domain name into an IP address, preventing access to resources by name.
- Commonly due to incorrect DNS server IP, unavailable DNS server, or firewall blocking DNS traffic.
- Symptoms include inability to browse websites by name, but can often ping by IP.
- Troubleshoot using `nslookup` or `dig` commands.
Memory trick: Domain Names Need Solving to connect.