DNAME definition
DNAME is a type of DNS (Domain Name System) record that allows redirecting domain namespace subtrees to other domains. Unlike CNAME records, which are tied to a single name in the DNS tree, DNAME records affect all subdomains under a specific domain.
DNAME records can be useful when you want to migrate a whole subtree to another domain without creating individual CNAME records for every subdomain. Despite this, DNAME records are relatively rare — they are not supported uniformly across all DNS software and can complicate maintenance for administrators.
See also: dynamic DNS, DNS resolution, DNS, DNS redirection, DNS record, DNS query, DNS CNAME record, fully qualified domain name
How DNAME records work
To illustrate how DNAME records fit in the DNS resolution, let’s take “sub.one.com” as our example query. When a DNS resolver queries “sub.one.com,” it follows the DNS tree from the root down through “com,” then “one,” and finally “sub.” If you set a DNAME record at “one.com” to point to “otherdomain.com,” it would tell DNS resolvers that any subdomain under “one.com” should be treated as part of “otherdomain.com” (so “foo.one.com” should be treated as “foo.otherdomain.com”).
By contrast, a CNAME record at “sub.one.com” could point directly to another domain, but it would only work for that specific node. DNAME acts as a namespace alias for all subdomains, not just a single name — when a DNAME record is present, the DNS resolver synthesizes a CNAME-like redirection for any query below the DNAME's owner name.
