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 (Address)
Using an A record you can associate a hostname with an IP 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.
*MX records (Mail Exchanger)
MX 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 (for example mail.hotmail.com). You cannot add IP addresses as MX records.
If you modify the MX record 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 (Alias)
The record is similar to the A record. However, while for the A record you need to specify an IP address, for the CNAME you need to specify another host name (for example user.my_domain.com).
TXT 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 Sender Policy Framework (SPF http://www.openspf.org/) 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 domain. The "~all" string at the end specifies that the mechanisms listed are all that should be used for matching. It also defines a SOFTFAIL policy.
SRV 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
service: the symbolic name of the service.
proto: the transport protocol of the service.
name: the domain name for which the record is valid.
TTL: the DNS time to live field.
class: the DNS class field (this is always IN).
priority: the priority (lower value means higher priority).
weight: A relative weight for records with the same priority.
port: the TCP or UDP port on which the service works.
target: 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-existent names. It is specified by using a "*" as the leftmost label (part) of a domain name (*.my_domain.com).