Resolvers must be able to access at least one name server. The resolver either uses that name server's information to answer a query directly or pursues the query using referrals to other names servers. A resolver will typically be a system routine that is directly accessible to user programs. Therefore, no protocol is necessary between the resolver and the user program. Name servers know the parts of the domain tree for which they have complete information.
Authoritative information is organized into units called ZONEs.
Zones can be automatically distributed to the name servers which provide redundant service for the data in a zone. The cache stores the results from previous responses. Upon receiving a user query, it will check this local storage to see if the answer is available locally. A resource record is contained in a file commonly called a zone file and is used to define objects. The Name Server record identifies an authoritative name server for a domain.