Apex Alias Records

Traditionally, the use of CNAMES at the apex of a domain has been discouraged and eventually forbidden by the protocol specification. However, modern usage of CDNs and outsourced cloud environments have driven the need for the ability to point the apex of a domain to resources outside of the domain. Apex Alias (APEXALIAS) provides a way for domain administrators to provide DNS CNAME functionality at the apex (or root) of a domain.

At query and resolution, the UltraDNS resolvers will chase the Apex Alias, in the same way that a recursing resolver would, and return the results of the chase in the answer to the query. Apex Alias functionality supports both IPv4 and IPv6 address resolution, returning A and AAAA records as appropriate. UltraDNS also has built-in support for the edns0-client-subnet (ECS) specification, meaning that caching resolvers that pass in the client subnet will be able to take advantage of ECS functionality when querying for the zone apex.

An Apex Alias record consists of the following fields:

• Host - Provide a valid hostname.

  • By providing a Host, this will become a Host Alias record type.

• Points To: Provide the hostname the Apex Alias is pointing to.

• TTL - The Time to Live (TTL) for the record. You can provide this value as either an integer or an annotated value (1h = 1 hour).

  • This field is not required, and will be set to the default value if left empty.