ANAMEs or “Apex Aliasing” provides one of the most sought after protocol violations on the web today. In other words, it lets you do this:
example.com. IN CNAME some.other.hostname.example.
Under normal circumstances, this is a protocol violation, because of the “CNAME cannot contain other data rule” specified way back in RFC 1034 but emphasized in RFC 1092:
“A CNAME record is not allowed to coexist with any other data”
And since your zone apex must have matching SOA record, not to mention the NS RRSet, putting a CNAME here would break the rule, and in the process break your DNS.
But a lot of people really want to do it, and the reason you’re reading this page is probably because you want to do it. Further, given the prevalence of use-cases like pointing your domain at a CDN or other external platform, it was inevitable that DNS providers would come up with a way to do it.
Enter the ANAME, which is like a CNAME for your zone apex, at least you can use them in your settings that way. Under the hood, these records get flattened into A records, but you don’t need to know about the gory details (there is an entire section about it in our book Managing Mission Critical Domains and DNS for the true keeners).
Suffice it to say that you can add your domain apex as you would any other CNAME in the DNS editor, the system will give you a gentle notice that this will be implemented as an ANAME record, and you are off to the races.
Enjoy that CDN! Or whatever.