SRV record
A DNS record that maps a service name to a host and port. Used by SIP, XMPP, and modern service-discovery tools.
SRV (Service) records associate a named service with a hostname and port. They're more specific than an A record because they tell you exactly which port to connect on.
_sip._tcp.example.com. SRV 10 60 5060 sipserver.example.com.
Reading left to right:
_sip._tcp— service is SIP over TCP.10— priority (lower = preferred).60— weight (load balancing among same-priority records).5060— port.sipserver.example.com.— target hostname.
Common SRV use cases
- SIP / VoIP. Discovering where to connect for a phone call on a domain.
- XMPP / Jabber. Same idea for chat protocols.
- Microsoft Teams / Skype for Business. Federated calling setup.
- Minecraft.
_minecraft._tcp.example.comlets you run on non-default ports. - Some Active Directory features.
Why SRV isn't widespread for HTTP
HTTP intentionally doesn't use SRV. The web defines its own service discovery via well-known ports (80, 443) and A/AAAA records. There was an attempt (HTTPSSVC / HTTPS RR) in 2020 to standardize SRV-like behavior for HTTPS, and it's slowly rolling out — but for most SaaS use cases you can ignore SRV entirely.
If you're building a non-HTTP service that customers might connect to from a custom domain (a self-hosted Mattermost, a SIP gateway), SRV is the right way to expose it.