Resolvers are the clients that access name servers. Programs running on a host that need information from the domain namespace use the resolver. The resolver handles:
In Windows 2000, the resolver is just a set of library routines that is linked into programs such as telnet and ftp . It's not even a separate process. It has the smarts to put together a query, to send it and wait for an answer, and to resend the query if it isn't answered , but that's about all. Most of the burden of finding an answer to the query is placed on the name server. The DNS specs call this kind of resolver a stub resolver .
Other implementations of DNS have had smarter resolvers that can do more sophisticated things, such as build up a cache of information already retrieved from name servers. In fact, Windows 2000 includes a caching resolver.