In addition to enabling DNS clients to locate network resources by name, DNS also provides information about network services ...

In addition to enabling DNS clients to locate network resources by name, DNS also provides information about network services and the servers that host those services. This information is contained in resource records that you add to a zone to associate the network service with its host server. For example, to identify the mail exchanger for a domain, you add an MX record to the zone that corresponds to the domain. You can also use service (SRV) records to support general-purpose service location for the computers in a domain.