DNS record types and how to use them

The main purpose of the Domain Name System (DNS) is to translate user-friendly names to numerical IP addresses. These names are translated with the utilization of DNS resource records. The DNS resource records are stored on a DNS name server. Using the DNS Manager section in the Control Panel, you can modify the following types:

A records

Using an A (Address) record you can associate a hostname with an IPv4 address. For example, if you have a server at your office and you need to name it office.my_domain.com, you can use an A record to do that.

AAAA records

You can add AAAA records to point a hostname to a specific IPv6 address.

MX records

MX (Mail eXchange) records are used to define where email messages for a given domain name will be routed to. It can be either a hostname under your domain name (e.g. mail.my_domain.com), or can be a name of a third-party mail server (e.g. mail.hotmail.com). You cannot add IP addresses as MX records.

If you modify the MX records for your domain name, please make sure that the server you have defined as MX for your domain name is configured to accept email messages sent to your domain name.

CNAME records

The CNAME (Canonical NAME or Alias) records are similar to the A records. While you need to specify an IP address for the A record, for the CNAME record, you need to specify another hostname (for example user.my_domain.com).

TXT records

TXT (TeXT) records give you the option to associate some text with a host or other name.
For example, the TXT record is used to define the SPF (Sender Policy Framework) information record which may be used to validate legitimate email sources for a domain.

An example of an SPF record is:

my_domain.com. IN TXT "v=spf1 a mx ~all"

"v=" defines the version of SPF used. The "a" and "mx" strings specify the systems which are permitted to send messages for the domain. The "~all" string at the end specifies that the mechanisms listed are all that should be used for matching with a SOFTFAIL policy.

SRV records

SRV (SeRVice) records are more complex records which are used to define the hostname and the port for specific services.

SRV records are added in the following form:

_service._proto.name TTL class SRV priority weight port target

The "service", "proto", and "name" strings define the symbolic name, transport protocol, and domain name of for which the record is valid. The "class" string defines the DNS class field (which is always IN). The "priority" string indicates the priority of the DNS record (lower value means higher priority), and the "weight" string shows the relative weight for records with the same priority. The "port" string can be either TCP, or UDP depending on the port on which the service works, and "target" shows the hostname of the machine providing the service.

SRV records are used for services such as XMPP, Client SMTP Authorization, SIP, etc.

Wildcard DNS records

A wildcard DNS record is a record that will match requests for non-existing names. It is specified by using a "*" (asterisk symbol) as the leftmost label (part) of a domain name (e.g. *.my_domain.com).