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SRV · type 33

Locates a service: host, port, priority and weight.

Last updated 5 Oct 2026 from the IANA RR TYPE registry

Short answer

An SRV record lives at _service._protocol.<domain> and tells clients which host and port provide a service, with priority (try lowest first) and weight (share load among equal priorities).

Type
SRV
Code
33
Defined in
RFC 2782
IANA description
Server Selection
Field: Priority
Lower first
Field: Weight
Relative share among equal priorities
Field: Port
TCP/UDP port
Field: Target
Host name; “.” means the service is not offered

How it works

It is used by protocols that look services up by name, such as SIP, XMPP, LDAP and Microsoft Teams/Skype federation, and by mail client autodiscovery for IMAP and submission (RFC 6186).

Example

_imaps._tcp.example.com.  3600  IN  SRV  0 1 993 mail.example.com.

Example uses reserved documentation names and addresses (RFC 2606, RFC 5737, RFC 3849).

Common mistakes

  • Leaving out the leading underscores in the name.
  • Pointing the target at a CNAME.

How to check yours

Each service defines its own SRV name, so check the vendor’s instructions for the exact _service._protocol label. A target of “.” explicitly says the service isn’t offered at this domain, which clients treat differently from a missing record: they stop looking instead of trying fallbacks.

Related record types

MXSays which servers receive email for the domain.APoints a name at an IPv4 address.

Sources

Sources

  1. IANA: Resource Record (RR) TYPEs registry · checked 5 Oct 2026
  2. RFC 2782 · checked 5 Oct 2026