Questions about aliases and cnames.

Kevin Darcy kcd at
Tue Mar 13 22:36:49 UTC 2001

This is really up to you. You can have as many aliases as you want pointing to a
single name. In fact, I generally prefer this approach -- as opposed to just having
multiple A records pointing to the same address -- since it's only 1 A record to
modify if the address changes, and there is no reverse-record ambiguity (clearly
the PTR will point back to the owner of the A record, not any of the alias names).
But there are some situations in which A records must be used (e.g. where a machine
has multiple names in different zones, and some of the customers only have access
to one of those zones).

Another thing to consider is that aliases can't be used as targets for other
records in DNS (NS records, MX records, etc.). So you couldn't use, say, "www" as
the target of an MX or NS record, if it's an alias.

Note also that CNAMEs can't co-exist with records of other types, so if, for
example, you want the zone top of a registered domain, e.g. to refer to
a web server, e.g. as in the URL, then, because
already owns an SOA record and at least one NS record, it would have to be an
A record; it cannot own a CNAME. You're stuck using an A record in that case.

- Kevin

lawrence.a.kravets at wrote:

> Hello all.  I have a couple of quick Bind 9.1 questions.
> Should we have multiple aliases for a single device?
> If the answer is no, I was wondering what the proper way this should be done and
>  why.
> Here is a example.
> server         IN   A
> www       IN   CNAME     server
> ftp       IN   CNAME     server
> telnet         IN   CNAME     server
> Thanks for your input,
> Larry
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