This article discusses in detail DNS records of the SRV and NAPTR types. For general instructions on DNS records and how to set them up in the customer administration, see DNS - Domain Records.
In this article you will learn:
- What are the SRV records used for
- How to enter SRV records correctly
- Examples of SRV record settings
- How a NAPTR record works
- Frequently Asked Questions
Purpose of SRV records
The Service Record (SRV) is used to specify information about available host services. Common examples of these services include XMPP (instant messaging protocol), SIP (Internet telephony signaling protocol), and LDAP (directory server data access and storage protocol).
The SRV record type cannot be used to specify a port that is running a service that does not support this record type.
For example, if you want to run a Web site (HTTP or HTTPS) on a port other than the normal port, you must make the settings on the server. You cannot set this port in an A, AAAA, or SRV record.
Entering SRV type records
For general instructions on setting up DNS records in the customer administration, see DNS - Setting up domain records.
If the domain uses other DNS servers, automatic or manual changes to WEDOS records will not affect its behavior.
SRV records have a specific name and data format.
SRV record name
The symbolic name of an SRV record is usually of the form _sluzba._protokol, for example. _sip._udp.
Add any subdomain to the end of this symbolic name, for example _ldap._tcp.subdom.
SRV record data
The SRV record data consists of the following parts:
- Priority: a positive number determining which record will be evaluated first (the one with the lowest number); the system evaluates other records only if the priority service is unavailable.
- Weight: relative weight for records with the same priority, used to distribute the load.
- Port: The TCP or UDP port on which the service is listening.
- Target: the hostname of the server providing the service.
Follow these rules when completing an SRV record:
- Give the main server the lowest priority number but the highest weight.
- The hostname should be in the form of a domain, not an IP address.
A generic SRV record looks like this:
Name TTL Type Data (symbolic name) 300 SRV (priority) (weight) (port) (hostname)
Examples of SRV records
Example: recording SRV for SIP over TCP on port 5060 with the target tel.wds-test.cz.
NAPTR record type
The Name Authority Pointer (NAPTR) record is often used in combination with SRV records, most commonly for Internet telephony purposes to map SIP. Follow your service provider's instructions when entering it.
Frequently Asked Questions
Question: How do I get DNS to point HTTP to a port other than 80 (or 443 for HTTPS)?
A: You cannot do this in DNS, you must set it on the server.