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

[Joe Abley]

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.


Joe