[dns-operations] "EarthLink Criticized for DNS Redirects"

Mark Andrews Mark_Andrews at isc.org
Mon Sep 18 15:30:26 UTC 2006

> Le 2006-09-18 à 09:54, Barry Greene (bgreene) a écrit :
> > Yes, that is the practice turned policy that I'm talking about.
> Thanks for the clarification.
> It may be useful to note that it's a recommendation for ISPs, the  
> next time you mention it. Your comment 'much like Canada who has all  
> customers go through their "port 25" infrastructure' makes it sound  
> like some kind of draconian centralised government control of  
> packets. Although some big residential ISPs in Canada do this, many  
> residential ISPs do not (and I haven't yet heard of business-grade  
> internet access services that implement it, although there may well  
> be some.)
> The trouble with 25/tcp redirection is that it breaks mail submission  
> from clients to mail services not run by their ISPs. Since mail  
> clients have widely-available alternatives these days, however (most  
> clients will let you specify a port) this turns out to be a non-issue.
> There's an unfortunate analogue between the 25/tcp-overloading and  
> the DNS, however. There are a big class of requests sent to 53/udp  
> which are suitable for redirection to a local cache, but there are  
> many notable exceptions.
> Maybe it's reasonable to look at a couple of examples of things that  
> are really unsuitable for redirection (AXFR/IXFR and UPDATE, say) and  
> to standardise alternate ports for them to listen on.

	Anything with rd=0.

> Joe
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