Apex Domain

The apex domain is the domain you actually registered, with nothing in front of it: `example.com` rather than `www.example.com` or `blog.example.com`. It is also called the zone apex, naked domain, or bare domain. The apex is where the SOA and NS records live, and historically it cannot hold a CNAME because that would conflict with those required records. This is why pointing the apex at a CDN often requires provider-specific workarounds like ALIAS, ANAME, or CNAME flattening records. Picking apex versus www as the canonical hostname is a foundational decision for every site.