If a host cannot be reached by its name but can be reached by its IP address, what does this indicate?

If a host cannot be reached by its name but can be reached by its IP address, what does this indicate?

• A. The host is reachable by name but not by IP, indicating a hostname resolution issue.
• B. The host cannot be reached by its name but can be reached by its IP address, indicating a DNS problem.
• C. The network is down entirely.
• D. The firewall blocks access to the hostname only.

Answer: (B)

When you can reach a host by its IP address but not by its hostname, the issue is with name resolution. The network path to the host is fine, since the numeric address works, but translating the human-friendly name into that address isn’t succeeding. This points to DNS problems: the DNS server you’re using may be misconfigured, unavailable, or lacking the necessary records; or your local resolver/cache may be stale or misconfigured (for example, an incorrect DNS suffix or hosts file entry). To understand and fix it, you’d verify DNS resolution directly (for example, using nslookup or dig to see what IP the name resolves to), check that you can reach the DNS server itself, and review your DNS settings or hosts file. If the DNS query returns an error or no address, that confirms a DNS problem, since the host is actually reachable by its numeric address. Why the other scenarios don’t fit: if you couldn’t reach by IP at all, the network path itself would be down or blocked; if only the hostname were blocked by a firewall, you’d still face DNS-related symptoms but the core issue would be different, since reaching by IP should still work. The described symptom uniquely points to DNS name-resolution problems.

When you can reach a host by its IP address but not by its hostname, the issue is with name resolution. The network path to the host is fine, since the numeric address works, but translating the human-friendly name into that address isn’t succeeding. This points to DNS problems: the DNS server you’re using may be misconfigured, unavailable, or lacking the necessary records; or your local resolver/cache may be stale or misconfigured (for example, an incorrect DNS suffix or hosts file entry).

To understand and fix it, you’d verify DNS resolution directly (for example, using nslookup or dig to see what IP the name resolves to), check that you can reach the DNS server itself, and review your DNS settings or hosts file. If the DNS query returns an error or no address, that confirms a DNS problem, since the host is actually reachable by its numeric address.

Why the other scenarios don’t fit: if you couldn’t reach by IP at all, the network path itself would be down or blocked; if only the hostname were blocked by a firewall, you’d still face DNS-related symptoms but the core issue would be different, since reaching by IP should still work. The described symptom uniquely points to DNS name-resolution problems.