What type of DNS query involves a resolver taking full responsibility for finding the requested domain's IP address?

A recursive lookup is a type of DNS query where the resolver takes full responsibility for obtaining the requested domain's IP address. In this process, when a resolver receives a DNS query, it will either respond with the cached IP address or take the necessary steps to find the IP address from other DNS servers. This means that if the resolver does not have the address available locally, it will contact additional DNS servers, following the chain of authoritative nameservers until it either finds the desired IP address or determines that the domain does not exist.

During a recursive lookup, the client that made the request does not have to perform any further queries on its own; the resolver does all the work and provides a final answer back to the client. This contrasts with iterative lookups, where the resolver may return partial results and the client might need to query other servers based on that information. Forward lookups and reverse lookups are specific types of queries that target different aspects of DNS functionality—forward lookups map domain names to IP addresses while reverse lookups do the opposite, resolving IP addresses back to domain names. However, neither of these types indicate full responsibility taken by the resolver in the same sense as recursive lookups.