This article is part three in a series dedicated to the DNS Management; DNS Record Types Explained. It is recommended that you read the first two entries in this series, “Registrars and Nameservers,” and “Zones, Record Types, and Record Composition” before continuing with this article.

In this part, we will discuss a few of the more commonly used record types and when you might use them.

A Records

A Records are the most basic type of DNS record and are used to point a domain or subdomain to an IP address. Assigning a value to an A record is as simple as providing your DNS management panel with an IP address to where the domain or subdomain should point and a TTL.

A Record listing in the GoDaddy DNS Management Panel.

A Record listing in the GoDaddy DNS Management Panel.

The screenshot above is a sample of A Record listings of different types. You can see the use of the wildcard ( * ), @ symbols, and named host name entries. Here, the primary naked domain record (@) and blog subdomain point at the same IP address, but are separate records and can be changed individually at any time. A Records are only able to take an IP address as their value and you can point the same domain/subdomain to multiple IP addresses by adding another A Record with the same name but with a different IP address for the value.

You would want to use an A Record for your DNS entry if you have an IP address that the domain/subdomain should point to or if you want to establish a domain/subdomain to be used as the place to point a CNAME. You can find out more about why you might want to do this in the CNAME portion of this article.

CNAME

CNAME records are another commonly used type of DNS entry and are used to point a host/name to another host/name.

CNAME record listing in the GoDaddy DNS Management Panel.

CNAME record listing in the GoDaddy DNS Management Panel.

In the screenshot above, you can see immediately that one of the important differences from A Records is that the value portion of the record is required to be an existing subdomain/domain. You can see that the “journal” host/name points to my blog.iamrobertv.com A Record, which points to 198.101.164.57. What this means is that if I ever changed the value of the blog subdomain, then the journal subdomain will also inherently have its value changed.

As a host, we can use CNAMEs for customers as a means of being able to change the IP address of a server or cluster of servers transparently and without users having to make their own DNS adjustments. You can see an example of this in the store host/name that points to a cluster of servers of servers that sit behind the thor.openhostingservice.com subdomain. Finally, you can see the use of the @ symbol to indicate that the www host/name should point to the naked domain and use its value, which when you see the A Record sample image above, points to 198.101.164.57. This also means that if the value of the naked/primary domain changes, the record of www will end up being affected accordingly.

MX Record

Mail Exchanger (MX) records are used to help route email according the domain owners preference. The MX record itself specifies which server(s) to attempt to use to deliver mail to when this type of request is made to the domain. They differ from A Records and CNAMEs in the way that they also require a “priority” value as a part of their entry. The priority number is used to indicate which of the servers listed as MX records it should attempt to use first.

mx_record

In the screenshot above, you can see that I am using two MX records that have separate priority values and point to different subdomains. These subdomains are pointed at two different email servers that are designated to handle email. The MX record with the lower priority number (0 in this case) is the first to be tried for email delivery. If this server is unable to handle the mail request, the next lowest priority number is used, which in this case would be 10.

Some email providers have only one MX record and some have well over two. The number of MX entries you will need to create depends largely on the mail provider and how they expect the load on these email servers to be handled.

You’ll notice the host name here is designated as the naked/primary form ( @ ). If you wanted to receive mail on a subdomain, you would adjust the host/name accordingly and ensure your email provider is setup to handle email from the subdomain.

TXT Record

A TXT record is used to store any text-based information that can be grabbed when necessary. We most commonly see TXT records used to hold SPF data and verify domain ownership.

TXT Record listing in the GoDaddy DNS Management Panel.

TXT Record listing in the GoDaddy DNS Management Panel.

The screenshot above gives an example of how a TXT value would be formed for both an SPF entry or a ownership verification for the naked/primary host/name using the @ symbol. If you need to verify or provide an SPF record for a specific subdomain, then you will need to use the appropriate host/name in place of the @ symbol. The rule of thumb for TXT records is that they require a an attribute name, follow by an equals sign, followed by a value for the attribute. You can use this to relay any sort of information you’d like using a DNS record, so long as you have a purpose for it and the record is properly formatted.

We won’t go into the details of properly formed SPF records and what their different pieces mean, but these will commonly be supplied to you by the mail provider you are working with. In the same way, places that require domain verification through use of a TXT record will also provide you with a properly formatted TXT record value to use.

Final Thoughts

Managing your own DNS can be a tricky endeavor, especially if you haven’t ever considered what this means or ever even seen a DNS record. Ideally this series of articles will help you understand the general  how a website’s DNS works for a domain from the time it is typed into the browser to the time your name servers handle the request. Although it can be rather easy to understand the record types themselves, knowing about nameservers, registrars, and how a specific set of DNS records gets chosen and used is a little more difficult to navigate, but is just as essential to know.

5 thoughts on “DNS Management: Record Types and When To Use Them

  1. DNS Truth

    (A) records point hosts (not domains) to IP addresses.

    Domains contain host records (and other resource records). Host records point to IP addresses.

    A CNAME record is an alias for an (A) record. It points to another host record, not to another domain/subdomain.

    Your terminology in this article is so innacurate as to be confusing and a disservice to any readers. In addition to the above, what is a “host/name?” Do you mean “hostname?” Or do you mean “host” or “name?” The latter does not make sense, ergo your use of the heretofore unseen “host/name” term/phrase/whatever makes no sense.

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