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What is an A Record?

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Heather Oliver is a Technical Writer for Constellix and DNS Made Easy, subsidiaries of Tiggee LLC. She’s fascinated by technology and loves adding a little spark to complex topics. Want to connect? Find her on LinkedIn.

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Getting a B in school might be acceptable, but a B in DNS won’t cut it. In order for a domain to be resolved properly you must have an A—an A record, that is. Besides, while there are several different DNS record types, a B record isn’t one of them. What does A stand for exactly? It stands for Address, and every single device that connects to the internet has to have one, which is why A records are integral to any DNS configuration.

A Record Explained

A records are primarily used for DNS lookups and are the most commonly used record type. In a way, they’re like the central nervous system of DNS, as most other record types rely on their functionality. This is because A records map fully qualified domain names (FQDNs) to numerical IPv4 addresses—the defacto internet protocol still used by most devices. 

Did you know?: We’re almost out of IPv4 addresses, which is where AAAA records come in. They function the same as A records, but utilize IPv6 addresses. Currently, they coexist, but eventually, IPv6 will replace IPv4 entirely.

Another important aspect of an A record is that it can be pointed to a subdomain or used at the root of a domain. The root, also known as a “naked domain,” is typically represented by an @ symbol in your DNS record configuration or can appear as a blank name value in your zone file (as seen in the example below). 

DNS A records Explained

DNS A Record Example

First, let’s visualize the differences between FQDNs, the root, and subdomains.


Root (naked) → 

Subdomain → news.constellix or

DNS A Record Example - A records Explained - What is an A Record?
DNS A Record Example

DNS A Record Structure - A records Explained - What is an A record?
A Records Explained

Now, let’s look at the structure of an A record.

A (host)                Points to (IPv4 address)    TTL (Time to Live)

@ (root)           →     300

news (subdomain)       →     300

services (subdomain)  →     300

That’s a Wrap on A Records

In summary, an A record is a DNS file that specifies the location of the server your domain is hosted on. This is needed so that resolvers can find your domain on the web. A records can point to a FQDN, a subdomain, or used at the root. You can also have multiple A records for the same domain that point to different IP addresses, depending on your DNS configuration.

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