Which DNS query is used when the resolver must query other servers to obtain the answer?

Which DNS query is used when the resolver must query other servers to obtain the answer?

• A. Iterative
• B. Non-iterative
• C. Cache query
• D. Recursive

Answer: (D)

In DNS, when the resolver needs to obtain the final answer by asking other servers, it uses a recursive query. With a recursive query, the local DNS server takes responsibility for the entire lookup: it will contact the appropriate root server, then the top‑level domain servers, and finally the authoritative servers as needed, until it finds the exact record or a definitive failure, and then it returns that result to the client. This is different from an iterative query, where each server responds with the best information it has and a referral to the next server for the client to query. The recursive approach simplifies the client experience because the client only talks to one resolver, which handles all the back-and-forth across the DNS hierarchy.

In DNS, when the resolver needs to obtain the final answer by asking other servers, it uses a recursive query. With a recursive query, the local DNS server takes responsibility for the entire lookup: it will contact the appropriate root server, then the top‑level domain servers, and finally the authoritative servers as needed, until it finds the exact record or a definitive failure, and then it returns that result to the client. This is different from an iterative query, where each server responds with the best information it has and a referral to the next server for the client to query. The recursive approach simplifies the client experience because the client only talks to one resolver, which handles all the back-and-forth across the DNS hierarchy.