In troubleshooting, you can reach a host by its IP address but not by its name. Which factor is most likely the cause of the name-based communication failure?

Introduction / Context:
When connectivity by IP works but name lookups fail, the network path is usually fine. The problem instead lies with name resolution—how a textual name maps to an IP address. Understanding typical name sources helps quickly narrow the root cause in Microsoft, Linux, and mixed environments.

Given Data / Assumptions:

• Pinging or connecting via raw IP succeeds.
• Attempting to reach the same host by its name fails or resolves incorrectly.
• Name resolution may rely on DNS, WINS/NetBIOS, mDNS, or local static files like hosts/LMHOSTS.

Concept / Approach:
Name resolution is a separate step preceding connection. If the IP path is good, then DNS records (A/AAAA), NetBIOS/WINS entries, or static mappings may be missing, stale, or misconfigured. For legacy Windows name lookups, LMHOSTS/WINS can override DNS; on Unix-like systems, /etc/hosts or nsswitch.conf order can affect outcomes. Thus, incorrect or missing entries in these static or server-side databases commonly cause “name works for some, not others” scenarios.

Step-by-Step Solution:

Verification / Alternative check:
Clearing resolver caches (ipconfig /flushdns, systemd-resolved, or browser cache) often fixes transient issues. Packet captures show DNS queries leaving the client and the responses (NXDOMAIN, SERVFAIL, or wrong IP), pinpointing the database error rather than a routing problem.

Why Other Options Are Wrong:

• The IP address itself: connectivity by IP is already proven to work.
• Subnet mask: would affect IP reachability, not just name resolution.
• Default gateway: misconfiguration would break IP paths, not only names.
• MTU size: impacts fragmentation/throughput, not basic name mapping.

Common Pitfalls:
Assuming firewall rules selectively block DNS but not application traffic; overlooking split-horizon DNS where internal/external names differ; forgetting that VPN DNS settings can override local resolvers.

Final Answer:
Static name sources such as an LMHOSTS file or a DNS database entry