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Re: Implement SRV DNS

From: Greg Hudson <ghudson_at_MIT.EDU>
Date: 2004-04-21 19:34:30 CEST

On Wed, 2004-04-21 at 13:18, John Peacock wrote:
> I meant the larger issue of how Active Directory attempts to turn DNS into
> something like a general purpose database protocol. The number of queries
> required to resolve AD records is quite obnoxious.

But their use of SRV records has nothing to do with any sin they might
have committed in this area. A bogus SRV lookup consumes no more
resources than a bogus A lookup. I can understand the temptation to
criticize Microsoft for their sins, but it really does derail the
discussion.

> > SRV records don't form a chain.
>
> Poor choice of words on my part. I meant that the Subversion client would need
> to track all possible answers and try them in order (after suitable timeouts if
> necessary). It is a much more complicated process than simply requesting an
> address from a name and trying the connection.

The ultimate output of a SRV resolution is the same as the output of an
A resolution: a list of IP addresses. (In the SRV case the order of
those addresses is well-defined, while in the A case it is not, but from
the application's point of view that doesn't matter.) It would be no
worse to try only the first address we see from the SRV lookup than it
is to try only the first address we see from the A lookup.

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Received on Wed Apr 21 19:34:56 2004

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