Zone Apex Alias (ANAME)

A top-level domain, such as domain.com, is called the apex in the domain zone file. Unlike subdomains, DNS servers expect the apex record’s value to be an IP address rather than an alias such as a CNAME. This creates issues for services that change their IP addresses frequently. To overcome the zone apex aliasing problem, different vendors have developed different mechanisms with varying names. The simplest approach is to run a shell script that periodically updates the zone file with the current IP address.

Service Records (SRV) are often used to address the zone apex aliasing issue for non-HTTP use cases.