A Records

An A record or Address Record is the most fundamental part of a DNS Record and it indicates the IP address of a given domain. In other words, it maps a domain name to an IP address. For example, the A Record maps Google’s domain name to its IP address, so that users can access the site through the web server. 

What Are A Records Used For?

The most common use of an A Record is for IP address lookups or, in other words, matching a domain name to an IP address. This enables users to connect with and load websites on their devices without users needing to memorize and type in the actual IP address. So, one could say that the main function of A Records is to make using the internet easier.

Apart from this, DNS A records are also used for operating a Domain Name System-based Blackhole List that enables mail servers to identify and block email messages from known spamming servers. In this situation, the email server will use the domain of the sending address to map it to an IP address and compare it to a database of known spamming servers’ IP addresses. If there is a match, the email server will reject the email. For this reason, it is important that businesses that use email extensively ensure that their A Records are in order to ensure the best email deliverability.

How Do A Records Work?

In mapping a domain name to an IP address, the user's web browser automatically carries out this process by sending a query to a DNS resolver, which, in turn, resolves the given domain name to an IP address which can then be retrieved from the web server. If the user enters an incorrect domain name or one that doesn’t exist, the DNS resolver will be unable to resolve an IP address and the user will receive an error in the browser.

In practice, this means that a user can enter any domain name, like www.google.com into their browser’s address bar, whereafter the DNS resolver matches Google’s IP address to the domain name. Once this match is made, the browser is able to load Google's website and the user is able to view it in their browser.

Apart from making the process of browsing the Internet easier for users, without A records that map domain names to IP addresses to enable users to view them, the internet would have been unusable.

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