What is an SRV record?

An SRV (Service) record is a DNS record that specifies the location and port of a specific service. It allows service discovery by clients without knowing the exact server hostname in advance. SRV records include priority, weight, port, and target hostname.

What services use SRV records?

SRV records are commonly used by VoIP (SIP protocol), instant messaging (XMPP), LDAP directory services, Microsoft services (Active Directory, Exchange, Lync/Teams), and many other protocols that need dynamic service discovery.

How do priority and weight work in SRV records?

Priority (lower value = higher preference) determines which server to contact first, similar to MX records. Weight is used for load balancing among servers with the same priority — a server with weight 10 will handle roughly twice the traffic of a server with weight 5.

SRV Records

SRV (Service) records specify the location of servers for specific services. They're used to enable service discovery without knowing the exact server hostname.

How SRV Records Work

Instead of hardcoding server addresses, clients query SRV records to discover where a service is located. This is commonly used for:

Email servers (SMTP, IMAP, POP3)
Video conferencing (SIP, XMPP)
LDAP directories
Custom services

SRV Record Format

_service._protocol.example.com.  IN SRV 10 5 5060 sipserver.example.com.

Components

_service - Service name (e.g., _sip, _http, _ldap)
_protocol - Protocol (e.g., _tcp, _udp)
Priority - Lower = preferred (0-65535)
Weight - Load balancing among same priority
Port - Service port number
Target - Server hostname

Common Examples

# SIP (VoIP)
_sip._tcp.example.com.  SRV 10 5 5060 sip.example.com.

# XMPP (Chat)
_xmpp._tcp.example.com. SRV 10 5 5222 chat.example.com.

# LDAP
_ldap._tcp.example.com. SRV 10 5 389 ldap.example.com.

Testing SRV Records

Use our SRV Lookup tool to check your SRV records.

Try it on your domain

See the theory in practice — run a SRV Lookup for your own domain.