If they did, the Internet would be full of DNS queries. Most DNS servers belong to ISPs. These machines are no different from many machines we use hardware wise, they simply have special Software that does most of the work. A client can get an IP address two different ways. The first way, and the fastest, is called iterative resolution.
Iterative resolution works in a fairly straightforward manner.
Clients simply ask the server to resolve a domain name for them. The server accesses its local database, finds the IP address, and sends it back. The second DNS resolution method is a little more complicated. The client requests a name resolved by the server. The server will first do a normal iterative look up, checking its own local database.