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Re: Reliable Cloud host ?
From: david raistrick <drais () icantclick org>
Date: Tue, 28 Feb 2012 15:50:51 -0500 (EST)

On Tue, 28 Feb 2012, Owen DeLong wrote:

But they don't have to... They can simply use getaddrinfo()/getnameinfo()
and let the OS libraries do it. The fact that some applications choose to
use their own resolvers instead of system libraries is what is broken.

Not always true - firewall software, for example, generally requires IP addresses in their rules (ipfw, pfsense, iptables, at least a few years ago) and for validly sane reasons (even some of our best kernel guys were not crazy enough to change that for ipfw).


Proxy software that supports high connection rates and connection churn generally prefer to cache the IP address internally because OS resolvers and the caches they read from just can't keep up [except in specificly well designed systems - which proxy developers can't expect blow joe to know how to do]. A stress test tool I'm working with just had to be modified for exactly that reason (and because adding more caches in front of AWS semiauthorative caches (due to split horizon) wouldn't solve anything. a short TTL is a short TTL is a short TTL....).

Some of those proxy developers claim that within the chrootwhatchamajiggy that their socket handling code runs they don't have access to the resolvers - so they have to store them at startup (see haproxy).



--
david raistrick        http://www.netmeister.org/news/learn2quote.html
drais () icantclick org             http://www.expita.com/nomime.html



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