Re: [dnsext] common resources from multiple names, sustaining performance and identifying primary names

Mark Andrews <marka@isc.org> Wed, 15 September 2010 06:02 UTC

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To: Douglas Otis <dotis@mail-abuse.org>
Cc: IETF DNSEXT WG <namedroppers@ops.ietf.org>
From: Mark Andrews <marka@isc.org>
References: <4C902324.1020005@mail-abuse.org>
Subject: Re: [dnsext] common resources from multiple names, sustaining performance and identifying primary names
In-reply-to: Your message of "Tue, 14 Sep 2010 18:36:36 MST." <4C902324.1020005@mail-abuse.org>
Date: Wed, 15 Sep 2010 15:56:00 +1000
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In message <4C902324.1020005@mail-abuse.org>;, Douglas Otis writes:
>   While aliasing a name is how common resources seen from multiple names 
> are normally handled, CNAME and the seldom used DNAME are not very 
> suitable for renaming large portions of the name/resource tree.  
> Resolvers that don't understand DNAME, and those that don't understand a 
> new aliasing paradigm will then need each node replaced with synthesized 
> CNAME records having 0 TTLs. It seems this approach on a large scale is 
> likely to result in a significant performance reduction.

Actually the TTL matches (or will [1] and it is shipping in current
nameservers) that of the DNAME which may or may not be zero and the
majority of caching servers on the planet already understand DNAME.
Anything that does DNSSEC validation is required to understand
DNAME.

[1] http://datatracker.ietf.org/doc/draft-ietf-dnsext-rfc2672bis-dname/

Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka@isc.org