What does the TLD server respond with in a DNS lookup?

• A. The root server's address
• B. The NS record for the domain
• C. The DNSSEC key
• D. The IP address of the domain's nameserver

Answer: (D)

In DNS, once the root directs you to the TLD, the TLD server provides a referral to the domain’s authoritative nameservers. To let your resolver actually reach those servers, the TLD may include glue records that supply the IP addresses of those nameservers. So the TLD’s response can include the IP address of the domain’s nameserver, allowing the resolver to contact the correct authoritative server and complete the lookup. The root’s address isn’t what the TLD responds with in this step, DNSSEC keys aren’t part of a normal referral, and while NS records name the authoritative servers, the IPs (via glue) are what enable direct access.