> Date: Fri, 23 Oct 2009 08:30:08 -0400
> From: dave.l...@pixelhammer.com
> To: freebsd-questions@freebsd.org
> Subject: DNS Question
>
> Good morning.
>
> I have been asked by my co-workers and sales why I always create a A
> record for new domains we host instead of a CNAME.
>
> The issue I run into lately with some domains is that a client has a
> website with a industry host such as frank.relator.com and he wants to
> have DNS point www.frank.com to frank.relator.com with a CNAME. The
> client does not want an A record for frank.com.
>
> Somewhere, in a class far far away, I was taught a DNS zone had to have
> a A record to function properly. I can't seem to locate anything in the
> RFCs.
>
> Am I wrong?
>
I think you are confusing basics of DNS records. you are partially correct in
that a DNS zone needs an initial A record to be able to translate a name to an
IP, but there is nothing wrong about setting up a CNAME to point to a record in
a different zone instead. you just cannot do a zone that has a CNAME only that
does not at some point to a valid A record. CNAMEs are forwarders only whereas
A records are actual lookups.
for proper way to set this up....
The A record would be assigned for the main name that you want to associate to
an IP address.
The CNAME record just relates a different name to that original name. this
allows you to change the IP address of the server and only have to update the
original A record instead of every DNS record for that server.
for small number of vhosts, this would not really be an issue, but imagine if
you were hosting a couple hundred vhosts from a single IP and then had to
change that IP because you switched your ISP. It would take you a LONG time to
update them if they were all A records, but only a couple of seconds if you had
it properly set up as CNAME's
www.bobshosting.com A 192.168.0.1
www.vhost1.com CNAME www.bobshosting.com.
www.vhost2.com CNAME www.bobshosting.com.
www.vhost3.com CNAME www.bobshosting.com.
www.vhost4.com CNAME www.bobshosting.com.
-Sean
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