From RFC 1034 – Domain names – concepts and facilities: Domain names in RRs which point at another name should always point at the primary name and not the alias. This avoids extra indirections in accessing information. For example, the address to name RR for the above host should be: 52.0.0.10.IN-ADDR.ARPA IN PTR C.ISI.EDU rather … Read more
Yes, that’s an appropriate use of CNAMEs. In the discussions I’ve been part of, the arguments tend to go like this: Against CNAMEs: There is a (tiny) performance penalty, as the downstream DNS caches need to perform 2 DNS lookups, one for the CNAME and one for the A-Record the CNAME points to. Vague, bogus … Read more
It is possible to do this. At one point it was up in the air a bit until 4592 clarified that it should be supported. Just because it is possible doesn’t mean it is supported by all DNS providers. For example, GoDaddy won’t let you set up a wildcard in a CNAME record. In terms … Read more
CNAME records were originally created to allow multiple names that provide the same resource to be aliased to a single “canonical name” for the resource. With the advent of name based virtual hosting, it has instead become commonplace to use them as a generic form of IP address aliasing. Unfortunately, most people who come from … Read more