Apex Domain (Root Domain)

The apex domain, also called the zone apex, root domain or naked domain, is the name at the top of a DNS zone with no subdomain label in front: example.com rather than www.example.com.

Why it matters

The apex is special because the zone's mandatory SOA and NS records sit there, and a name holding other records cannot also be a CNAME. That is why you usually cannot point example.com at a hosting provider's hostname the way you can www. Providers work around this with proprietary features called ALIAS, ANAME or CNAME flattening, which resolve the target on the server side and return plain A records. Your apex typically also holds MX and TXT records for email.

Example

example.com.      300 IN A     203.0.113.10
www.example.com.  300 IN CNAME example.com.

The apex gets an A record; www is an alias to it. A web server then usually redirects one name to the other with a 301 so only one version is indexed.

Common mistakes

• Trying to create a CNAME at the apex, which conflicts with SOA, NS and MX.
• Serving different content on apex and www without a redirect.
• Forgetting an HTTPS certificate must cover both names.
• Confusing "apex" with "registrable domain": for example.co.uk, the apex of the zone is example.co.uk, not co.uk.

Related

• A record
• Subdomain takeover
• Redirects 301/302
• Guide: CNAME flattening and the apex domain
• Tool: Redirect checker

This page is general information written by our editorial team and updated when documentation changes. Servers and providers differ, so test changes safely first. See our editorial policy and disclaimer.