Stub resolvers

Stub resolvers reside on a device, host, or computer and process DNS queries for the operating system. Applications themselves typically don't need to worry about where the responses for their DNS lookups will come from or how they will obtain them. They simply make a call using a library function, such as gethostbyaddr() or gethostbyname().

The operating system then hands the query off to the local stub resolver, which is a minimal DNS stack that knows enough to find a full resolver (sometimes called a recursor) configured for the network, and forwards its query there.