An SRV record is intended to provide information on available services for your systems, most commonly used with SIP configuration. SRV records have a unique system for naming.
The naming system is an underscore followed by the name of the service, followed by a period, and underscore, and then the protocol, another dot, and then the name of the domain (the name of the domain you do not need to include in DNS Made Easy of course).
Example: _http._tcp.example-1.com. would be the service record for web requests for “example-1.com”.
An SRV record also has the following fields:
- Name – The naming system is an underscore followed by the name of the service, followed by a period, and underscore, and then the protocol, another dot, and then the name of the domain (the name of the domain you do not need to include in DNS Made Easy as it is appended to the end of your record).
- Host – The system that will receive the service.
- Priority – This acts the same way as the MX Level / preference in the MX record. The lower the number in the priority field, the more desirable the associated target. 0 is the highest priority (lowest number).
- Weight – Allows the zone administrators to distribute load to multiple targets (load balance). It is used to determine relative capacity and load between two SRV fields within the priority. Hits will be assigned proportionately by weight. This will allow the administrators to have a powerful and weak server and share the appropriate loads between those systems. 0 is the lowest load.
- Port – the actual port of the service offered.
SRV records allow specific services, such as VOIP or IM, to be be directed to a separate location.
Enabling your domain to use Google’s xmpp server is a good example to showcase. Google’s help article states that the SRV record should be in this format:
_xmpp-server._tcp.gmail.com. IN SRV 5 0 5269 xmpp-server.l.google.com.
Under “Add DNS Record”, you will need to enter the settings this way:
- Service: _xmpp-server
- Protocol: _tcp
- Host: chat (If you want to use the chat subdomain. Replace this with the subdomain that you want to us, or @ for the root domain.)
- TTL: 14400
- Type: SRV
- Priority: 5
- Weight: 0
- Port: 5269
- Points To: xmpp-server.l.google.com
- Zone File: This is where all the DNS records are stored for a domain.
- Service: This is the symbolic service name. e.g. _http, _ftp, _imap, ect.
- Protocol: The Protocol used by the service, usually either TCP or UDP.
- Host Record: This is the domain or subdomain you wish to use. The @ symbol is used to indicate the root domain itself. In our example the Host Record ‘ftp’ would be for the subdomain ftp.google.com and ‘@’ would be google.com itself.
- Points to: This is the destination server that the domain or subdomain is sending the traffic to.
- TTL: The ‘time to live’ value indicates the amount of time the record is cached by a DNS Server, such as your Internet service provider. The default (and lowest accepted) value is 14400 seconds (4 hours). You do not normally need to modify this value.
- Priority: This controls the order in which multiple records are used. As with MX Entries, lower numbers are used before higher numbers.
- Weight: This is similar to priority, as it controls the order in which multiple records are used. Records are grouped with other records that have the same Priority value. As with MX Entries, lower numbers are used before higher numbers.
- Port: This is used by the server or computer to process traffic to specific services, ensuring that all traffic comes through the door that it’s expected on.
- Target: This is the destination that the record is sending the traffic to. In the above example, the record would send traffic from chat.example.com to xmpp-server.l.google.com over port 5269. SRV records generally require advanced knowledge of server administration to use.
- Action: This allows you to modify or remove existing records.