FQDN pointing to CNAME record
Using Rackspace.com, which offers DNS service, I am attempting to point one domain EXAMPLE.NET to a dynamic DNS updated domain EXAMPLE.DYNDNS.ORG.
My problem is that when pointing the Fully Qualified Domain Name (example.net without any subdomain in-front) to the dynamic domain that is updated by the dyn service, I am given the response;
CnameRecord: Fqdn has already been taken by another resource record
while, in fact, there are no other records for this domain (other than the NS records that are required). I am not given this error when a subdomain is used, only when the fully qualified domain name is what is being acted on.
I found one article that gives me the insight to believe that one may point to a CNAME record from the FQDN (example.net).
CNAME records should not point to other CNAME records. This is mainly to avoid possible infinite loops.
CNAME records should not contain other resource record types (such as A, NS, MX, etc.). The only exception are DNSSEC related records (that is, RRSIG, NSEC, etc.) when the zone is signed.
Other resource record that point to the fully qualified domain name (FQDN) of a host (that is, NS, MX, PTR) should not point to a CNAME record.
My goal here essentially is to use a dns service to point my .net domain to a domain that is dynamically updated with my router since the server is stuck in a dynamic IP pool. Any advice?
Answer
The error message is exactly correct. You cannot create a CNAME RR because the domain already has NS RR (and in fact, also an SOA RR too) and CNAME is not allowed in combination with anything else (except DNSSEC RRs).
Your best bet is to use dynamic DNS to update example.net directly, instead of or in addition to updating example.dyndns.org.