A DNS server makes an iterative query as it tries to find names outside of its local domain when it is not configured with a forwarder.

• A. True
• B. False
• C. Not sure
• D. It depends

Answer: (A)

When a DNS server doesn’t have a forwarder, it resolves names by performing iterative queries itself. It starts by asking root servers for information about the highest level of the domain tree, then follows referrals to the appropriate top-level domain servers, and from there to the authoritative servers for the specific domain. Each response may provide either the requested answer or a referral to the next server to query. The server continues this step-by-step process until it either obtains the final address or determines it cannot be found. This is exactly how external names are discovered without a forwarder, so the statement is true. If a forwarder were configured, the server could hand off the resolution to that forwarder instead of performing iterative lookups itself; without a forwarder, iterative resolution is the path taken.