DNS Iterative vs Recursive Query Resolution
DNS resolution translates domain names into IP addresses through a chain of queries. Recursive queries have the resolver do all the work on behalf of the client, while iterative queries have each server return the best referral it knows. This distinction appears on CompTIA Network+, CCNA, and AWS certifications where DNS architecture is examined.
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5 CardsWhat does TTL control in DNS?
Which DNS record type maps a hostname to IPv4?
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What is the difference between iterative and recursive DNS queries?
In a recursive query, the DNS resolver does all the work and returns only the final answer to the client. In an iterative query, each server returns a referral and the resolver queries each in turn.
- Recursive: resolver bears the load
- Iterative: client/resolver follows the chain
Which DNS query type do most clients use?
Most end-user devices send recursive queries to their local DNS resolver (usually provided by the ISP or a public resolver like 8.8.8.8). Resolvers then use iterative queries when communicating with root and TLD servers.
What is a DNS root server?
A root nameserver is the first stop in resolving any domain. There are 13 sets of root servers (labeled A-M) distributed globally via anycast. They do not know the IP of every domain — they refer resolvers to the correct TLD nameserver.