# SIP SRV Records: DNS Setup for 3 Transport Types

Source: https://srvscripts.com/guides/sip-srv-records/
Updated: 2026-10-03
Publisher: srvScripts (https://srvscripts.com/)

SIP SRV records let phones, PBXs and trunk providers find your SIP server by domain name alone, and they give you failover between servers without touching a single phone. RFC 3263 defines the lookup: a client resolving `sip:example.com` first asks for NAPTR records to choose a transport, then for SRV records to get host and port, and finally for the A or AAAA address. This guide shows the records to publish and how to check them.

**Short answer:** Publish one SRV record per transport, `_sip._udp`, `_sip._tcp` and `_sips._tcp`, each pointing to an A/AAAA hostname (not a CNAME) with the right port: 5060 for UDP and TCP, 5061 for TLS. Use lower priority numbers for the primary server and a higher number for the backup, and weight to split load between servers of equal priority. Add NAPTR records if clients should prefer TLS, then verify with `dig SRV _sip._udp.example.com`.

In short: Publish one SRV record per transport, _sip._udp, _sip._tcp and _sips._tcp, each pointing to an A/AAAA hostname (not a CNAME) with the right port: 5060 for UDP and TCP, 5061 for TLS.

## Record format

An SRV record has four values after the type: priority, weight, port and target host.

```
; name                          TTL   class type priority weight port target
_sip._udp.example.com.          3600  IN    SRV  10       60     5060 sip1.example.com.
_sip._udp.example.com.          3600  IN    SRV  10       40     5060 sip2.example.com.
_sip._udp.example.com.          3600  IN    SRV  20       0      5060 sip-dr.example.com.
_sip._tcp.example.com.          3600  IN    SRV  10       0      5060 sip1.example.com.
_sips._tcp.example.com.         3600  IN    SRV  10       0      5061 sip1.example.com.
sip1.example.com.               3600  IN    A    203.0.113.10
sip2.example.com.               3600  IN    A    203.0.113.11
sip-dr.example.com.             3600  IN    A    198.51.100.20
```

Clients always try the lowest priority first. Within the same priority, weight sets the share of traffic, so the example sends about 60% to sip1 and 40% to sip2, and only uses sip-dr if both fail.

## NAPTR records for transport choice

NAPTR records tell clients which transports exist and which to prefer. Lower order values win. This set prefers TLS, then TCP, then UDP:

```
example.com. 3600 IN NAPTR 10 50 "s" "SIPS+D2T" "" _sips._tcp.example.com.
example.com. 3600 IN NAPTR 20 50 "s" "SIP+D2T"  "" _sip._tcp.example.com.
example.com. 3600 IN NAPTR 30 50 "s" "SIP+D2U"  "" _sip._udp.example.com.
```

NAPTR is optional. Without it, clients fall back to querying the SRV names directly, usually trying UDP first.

## Create them at your DNS host

In Cloudflare, cPanel Zone Editor or DirectAdmin DNS management choose type SRV and fill in the service (`_sip`), protocol (`_udp`, `_tcp`), priority, weight, port and target as separate fields. Keep the SIP host records DNS-only in Cloudflare; the orange-cloud proxy only handles web traffic and will break SIP if applied to the target hostname.

## Test the lookup

```
dig +short NAPTR example.com
dig +short SRV _sip._udp.example.com
dig +short SRV _sips._tcp.example.com
dig +short A sip1.example.com
openssl s_client -connect sip1.example.com:5061 -servername sip1.example.com