DNS A Record

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.

What is a DNS A record?

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 Record Example

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

FQDN →  www.Constellix.com. 

Root (naked) → constellix.com 

Subdomain → news.constellix or constellix.com/news

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A Record Structure

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

@ (root)           →   192.0.2.255     300

news (subdomain)       →   192.0.2.256     300

services (subdomain)  →   192.0.2.257     300

When are DNS A records Used?

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.