SRV record
also: Service record, SRV
A DNS record type that specifies the location and port of services available on a network, allowing clients to discover where services like LDAP, SIP, or Kerberos are hosted.
An SRV (Service) record is a DNS resource record defined in RFC 2782 that maps service names to the hostnames and port numbers of servers providing those services. Rather than requiring clients to know hardcoded server addresses, SRV records enable dynamic service discovery by publishing _service._protocol.domain format entries in DNS.
For example, a Kerberos realm might publish _kerberos._tcp.example.com SRV 0 0 88 kdc.example.com, telling clients that Kerberos TCP services run on port 88 at kdc.example.com. The numeric fields represent priority, weight, port, and target host, allowing load balancing across multiple servers.
SRV records are commonly used in enterprise Linux environments for services like LDAP directory queries, Active Directory integration, XMPP instant messaging, and VoIP protocols. Tools like dig or nslookup can query SRV records with dig _service._proto.domain SRV.