If a DNS server does not know the answer for a domain, what is its next step?

If a DNS server does not know the answer for a domain, what is its next step?

• A. It queries higher-level servers until it finds the correct IP address.
• B. It immediately retries the same server with a longer timeout.
• C. It relies on the local router to supply the IP address.
• D. It generates an error and stops resolution.

Answer: (A)

When a DNS server doesn’t have the answer cached, it resolves the name by walking up the DNS hierarchy. It starts by asking a root name server, which points it to the appropriate top-level domain server (like the .com server). That TLD server then refers it to the domain’s authoritative server, which provides the exact IP address. The resolver caches the result for future lookups. This stepwise escalation to higher-level servers is how name resolution finds an unknown domain. The other options don’t fit: retrying with a longer timeout doesn’t magically produce the IP, the local router isn’t involved in the actual name-to-address lookup, and generating an error would stop the process rather than complete the resolution.

When a DNS server doesn’t have the answer cached, it resolves the name by walking up the DNS hierarchy. It starts by asking a root name server, which points it to the appropriate top-level domain server (like the .com server). That TLD server then refers it to the domain’s authoritative server, which provides the exact IP address. The resolver caches the result for future lookups. This stepwise escalation to higher-level servers is how name resolution finds an unknown domain. The other options don’t fit: retrying with a longer timeout doesn’t magically produce the IP, the local router isn’t involved in the actual name-to-address lookup, and generating an error would stop the process rather than complete the resolution.