DNS records explained

Standard DNS Records

Our nameserver contains the following information for a domain.

  1. A records
  2. MX records
  3. CNAME records
  4. Text records

A Record (an IP address)

This tells the browser the IP address for the website. You will normally have a few A records, for example:

domain.com 84.51.238.253
www.domain.com 84.51.238.253

and then if another part of the site goes to a different address:

shop.domain.com 84.51.238.253

MX record (a mail exchanger record)

This decides what server e-mail is routed to. It is not an IP address, it is always in the format mail.domain.com or mail.novara.ie

If you want to point your mail to an IP address, you have to create an A record for it then point the MX record to that A record.

So you would create mail.domain.com pointing at the IP address then point your MX record at mail.domain.com.

You can have more than one MX record in case one goes down. MX records are given a priority from one to 50 and the lowest number is the server that gets preference. If that isn’t working the next one is used.

For example

domain.com (10) mail.domain.com
domain.com (20) mail2.domain.com

If mail.domain.com is not responding it gets picked up by mail2.domain.com

CNAME record (a canonical name)

This defines an alias for an A record. Generally a CNAME record points a hostname in a domain to another hostname in another domain.

For instance, we put CNAME records in place for our customers’ webmail a lot, we would point mail.domain.com at mail.novara.ie (where the webmail is hosted) and so you can access webmail from mail.domain.com, making it easier to remember.

Text Records

It is important to be careful with text records. They are normally used in relation to email and setting them up incorrectly can stop your mail from coming through.

What is DNS?

DNS can be considered something similar to a phone book. When you move from one location to another, your name stays the same, but your phone number may change. In order to point your name to the new phone number, you must contact the telephone service provider so they assign you the new phone number and update all directory information to reflect you as pointing to this new phone number.

In this way, the IP number can be compared to a phone number: When someone calls http://www.example.com/, your ISP looks at the DNS server, and asks “how do I contact example.com?” The DNS server responds: “It can be found at 84.51.238.253“. As the Internet understands it, this can be considered the phone number for the server, which houses the http://www.example.com web site.

The DNS records for your domain are kept on your hosting server in the place called DNS zone. When you register a domain by means of the control panel, all DNS records are automatically created for you, but in some rare cases you may need to add custom records to your DNS zone. An example would be when you want all email to be processed by an external mail server rather than by the built-in mail system. However, such user intervention requires knowledge of DNS configuration and clear understanding of what is to be done.

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