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Date:      Fri, 02 Jun 2000 22:41:27 -0700
From:      Doug Barton <DougB@gorean.org>
To:        Chris Fedde <chris@fedde.littleton.co.us>
Cc:        webmaster@wmptl.com, questions@FreeBSD.ORG
Subject:   Re: IP vs CNAME
Message-ID:  <39389A87.45BAE16A@gorean.org>
References:  <200006030454.e534sX101369@fedde.littleton.co.us>

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Chris Fedde wrote:
> 
> On Fri, 02 Jun 2000 21:27:27 -0700  Doug Barton wrote:
>  +------------------
>  | Nathan Vidican wrote:
>  | >
>  | > We are a relatively small ISP looking to grow. We're now starting to do
>  | > virtualhosting for people, and thus far I've been setting up
>  | > virtualhosts using cnames.
>  |
>  |      Why are you using CNAME's? You are needlessly doubling the traffic to
>  | your nameservers for every lookup. It's much better to define each host
>  | as an A record that points to the IP address of your vhost'ing server.
>  +------------------
> 
> This is obviously incorrect.  A DNS response has plenty of room in
> it for multiple records. The response to a cname query contains
> the CNAME, potentially many A records and several authority records.

	True, but just because there is room for it, doesn't mean that you need
to include it. It still represents a bandwidth cost, whether you feel
it's significant or not. At best, it's considered unfriendly to
needlessly use CNAME's, especially on a permanent basis. 

> The local name server is expected to cache these records to allow it to
> short circuit future requests for related data.

	Completely true, and totally irrelevant. I was talking about the
requests that you actually receive at your nameserver. 
 
> My current thinking on this issue is that it is better to use a
> CNAME record for name based virtual hosts since it preserves the
> validity of name matching between A and PTR records.

	And what value do you think that has for a vhost'ing web server? I'm
not going to spend a lot of time debating with you. If you weren't
interested in advice, you shouldn't have asked for it. :)

Doug
-- 
        "Live free or die"
		- State motto of my ancestral homeland, New Hampshire

	Do YOU Yahoo!?


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