About

The SRV (Service) record specifies the hostname and port for specific services. Unlike A records that only provide an IP address, SRV records include the port number, priority, and weight, enabling more sophisticated service discovery and load balancing.

SRV records are commonly used for services like SIP (VoIP), XMPP (chat), LDAP, and Microsoft services (Active Directory, Office 365). The format includes the service name and protocol as part of the record name.

The priority and weight fields enable advanced load balancing. Lower priority values are tried first, and weight is used to distribute load among records with the same priority.

Format & Example

Record Format

_service._protocol.domain.com. IN SRV priority weight port target.

Example

_sip._tcp.example.com. 3600 IN SRV 10 60 5060 sipserver.example.com.

SIP service over TCP is available at sipserver.example.com on port 5060, with priority 10 and weight 60.

Common Uses

•VoIP/SIP service discovery
•XMPP/Jabber chat servers
•Microsoft Office 365 autodiscovery
•LDAP server location
•CalDAV/CardDAV services

Best Practices & Tips

•Format: _service._protocol (e.g., _sip._tcp)
•Priority 0 is highest priority
•Weight is used for load balancing among same-priority servers
•Target must be a hostname with valid A/AAAA records

Related Record Types

A AAAA TXT

Related Tools

Propagation

Check SRV propagation

Service Record