Jonathan Duncan wrote:
athena IN A 192.168.1.1
www IN CNAME athena
We imprecisely say stuff like "www is a CNAME for athena." If we think
about the two lines together, though, we will say "192.168.1.1 is the
address for athena, and athena is the CNAME for www." So www is the
alias, and athena is the canonical name.
To quote DJB:
Don't use [CNAME] if there are any other records for [the fully
qualified domain name]. Don't use [CNAME] for common aliases; use [the
fully qualified domain name] instead. Remember the wise words of Inigo
Montoya: ``You keep using CNAME records. I do not think they mean what
you think they mean.'' (http://cr.yp.to/djbdns/tinydns-data.html)
What you say here sounds like you are confusing terms. It totally
confused me.
A FQDN (Fully Qualified Domain Name) has nothing to do with the type of
DNS record you use.
athena (NOT fully qualified)
athena.domain.com. (fully qualified)
Bind format zone snippet
# NOT fully qualified
athena IN A 192.168.1.1
www IN CNAME athena
# fully qualified
athena.domain.com. IN A 192.168.1.1
www.domain.com. IN CNAME athena.domain.com.
As you can see FQDN is not directly related to the type of DNS record
you use. Whether or not you should use a CNAME can be debated, and has
been. However the mention of using FQDN names is another discussion
altogether.
My Opinions:
Re: CNAMEs
CNAMEs are fine to use as long as they don't point to other CNAME
records. (See bottles-of-beer example) They are meant to simplify
management. Example: I have to change my IP for my server. If I use
CNAME records for www, smtp, pop3, secure, etc, etc, etc. I only have
one record to change. Really it is just a personal preference.
Re: FQDNs
Using an FQDN in a zone file is rarely necessary, unless pointing to a
name outside the zone the file is for. Refraining from using FQDN names
on all records keeps the zone file simple, easy to manage, and does not
incur much, if any, additional processing to parse.
--lonnie
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