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What is a DNS A record?

The "A" stands for "address" and this is the most fundamental type of DNS record: it indicates the IP address of a given domain. For example, if you pull the DNS records of cloudmysite.com, the A record currently returns an IP address of: 104.17.210.9.

IPv4 vs. IPv6​

It is important to note that A records only hold IPv4 addresses. If a website has an IPv6 address, it will instead use a "AAAA" record.

Example of an A Record​

Here is how an A record typically appears in a DNS configuration table:

Domain (Host)Record TypeValue (IP)TTL
@A192.0.2.114400

Note on Symbols:

  • The "@" symbol indicates that this is a record for the root domain.
  • The "14400" value is the TTL (Time to Live), listed in seconds.
  • The default TTL for A records is usually 14,400 seconds (240 minutes). If an A record is updated, it may take this long for the change to propagate globally.

Advanced Usage: Multiple A Records​

While the vast majority of websites only have one A record, it is possible to have several. High-profile websites often use multiple A records as part of a technique called round robin load balancing. This distributes incoming request traffic across several different IP addresses, each hosting identical content, to prevent a single server from becoming overwhelmed.

When are DNS A records used?​

1. IP Address Lookups​

The most common usage of A records is matching a domain name (like cloudmysite.com) to an IPv4 address. This enables a user's device to connect with and load a website without the user needing to memorize and type in numerical IP addresses. Your web browser handles this automatically by querying a DNS resolver.

2. DNS-based Blackhole List (DNSBL)​

A records are also used to operate DNSBLs. These lists help mail servers identify and block email messages originating from known spammer domains, acting as a critical layer of defense against junk mail.

Technical Resources​

If you want to learn more about the technical foundations of DNS A records, you can refer to the following:

  • Original 1987 RFC: Where A records and other DNS types were first defined.
  • DNS Fundamentals: For a deeper dive into how the broader Domain Name System works.

Need Help with Your DNS?​

If you are managing a high-performance website and need a Reliable Email Provider or professional domain management, ensuring your A records are configured correctly is the first step toward 100% uptime.

Would you like me to generate a technical diagram showing the step-by-step path of a DNS A record query from the browser to the server?