DNS & SRV Records Required for Geo-Redundant Setup

SRV Records

Note the following when using this article:

TTL means time to live. 

Priority v. Weight
We do not recommend changing weight for an SRV record because that will cause additional load on the server as it bounces traffic back and forth. Use priority instead. This still applies the load balancing concept, and still enables a failover, but it lessens the load on the server.

SRV DNS Records for UDP

Two new SRV DNS records for UDP Registrations:

SRV DNS Records for TCP

Two new SRV DNS records for TCP Registrations:

SRV DNS Records for TLS

Two new SRV DNS records for TLS Registrations:

Some devices use the _sips service header with TLS instead of _sip:

Some devices use the _sips service header with TCP instead of _sip:

• Reverse (PTR records) DNS entries MUST be set for all servers.
• SPF records must be set for all core servers. See your domain and email provider for more details

Once you have completed all of these configuration steps you can check if this was done correctly using our SRV Checker that can be found at https://devops.netsapiens.com/srvchecker/srvcheck2.php

Wildcard DNS Alias Records (OPTIONAL)

Wildcard DNS alias records are only used for an older and deprecated redundancy method called dual-reg. This method is still supported but it was superseded by SRV Active/Active methods. Unless your systems are still using legacy devices with legacy configuration, it should not be needed and it is better to not configure it.

If you will be configuring this option choose either two Wildcard CNAME or two Wildcard A records.  This may depend on what the DNS Server or Hosting Provider allows.