What Is an A Record?

DNS records, also known as zone files, are instructive text files in the form of DNS syntax and they give various information about a certain domain, such as how to handle requests related to that domain, which IP address is connected to it, who is responsible for that DNS zone, and so on. They are located on authoritative DNS servers which are specified in the Whois records for each domain name.

One of the most commonly used types of DNS records is the A record. A DNS A record holds essential information that allows users to access a specific website using its domain name. Let’s take a look at what exactly a DNS A record is and what it’s used for.

What is a DNS A Record?

An A record holds the most essential information about a domain: it contains the IP address associated with that domain. In other words, an A record has the instructions which connect the address of a computer through its hostname. The “A” in this type of record stands for address because it discloses the requested IP address.

How Does an A Record Work?

Let’s say you’re trying to access example.com. That domain points to a certain IP address, let’s say it is 1.1.1.1 (just for the sake of the example, we used one of Cloudflare’s IPv4 addresses, because it’s a beautiful number). So when you type the domain into your browser, it requests the IP address for example.com from a nearby DNS server. If that DNS server has the A record about that domain, it will retrieve it for your browser so you can access the website. If it doesn’t have it, it will send your browser to a DNS server that does.

So basically, the DNS A record gives the DNS server the necessary instruction (informational text) that can connect the domain name with the correct IP address.

Keep in mind that A records only deal with IPv4 addresses. The DNS record which is used for IPv6 addresses is the AAAA record.

What Is the Purpose of an A Record?

As you’ve realized, the main purpose and fundamental usage of an A record is to provide IP address lookup, i.e. to match a certain domain name (example.com) to its corresponding IPv4 address (1.1.1.1), like in the example we gave above. The invention of the Domain Name System, which allows users to access websites through their domain names rather than their IP addresses, using the internet and accessing content became a whole lot simpler. And the A record is key for things to function in this way.

A second usage for A records is to help blacklist and block emails from domains that are categorized as spammers. This is a part of the DNSBL (Domain Name System Blacklists) operation, which creates lists of websites with a history of spam emails, and then allows web administrators to block messages that come from websites on that blacklist.

Can There Be Multiple A Records for the Same Host?

While most websites only use one A record (because realistically, that’s all they need), there can be multiple A records for the same host. Having multiple A records for the same host is useful for high-profile websites with lots of traffic. These types of websites employ multiple A records as a part of a round-robin load balancing strategy, which allows site visitors to be distributed across several servers and IP addresses so that no single server is overloaded with traffic. 

Essentially, all visitors end up accessing the same content while allowing each server to handle the traffic load. When a user requests to access the website, the round-robin algorithm sends them to the server which has sufficient capacity to hold them.

Let’s say the website is backed by three servers. When a certain number of requests to access the website reach the round-robin algorithm, it distributes them across these three servers so as to balance the load. If 6 requests are sent, for instance, three of them may be redirected to the first server, two to the second, and one to third. 

A Few Words Before You Go…

Hopefully, our article has helped you better understand the meaning and purpose of A records in the Domain Name System. In a nutshell, A records perform the essential task for which the DNS was created – connecting the user to a website through the domain name rather than the IP address.

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