DNS lookup in FC2 still slow.

[Jack Bowling]

On Mon, Aug 02, 2004 at 08:53:58PM -0400, Ben Vitale wrote:
> Hi,
>    Yes, I realize this is an often asked question, and for that I 
> apologize.  I have the two lines..
> 
> alias net-pf-10 off
> alias ipv6 off
> 
>    ..in my /etc/modprobe.conf, and I have restarted several times since 
> they were put in place.  They have had no effect, and I don't think IPv6 
> is the culprit anyway.. my ifconfig shows all regular IP addresses. 
>    I checked the ping times of my nameservers, and the one at the top 
> of /etc/resolv.conf has the best times - on average, 8.5ms.  I would 
> assume this is just a Comcast provider problem, but this was not an 
> issue until I upgraded to FC2.

Ben - I wonder if it is a problem with ECN on the nameserver or somewhere
on the route? First check to see if you have ECN turned on in your kernel:

cat /proc/sys/net/ipv4/tcp_ecn

If you get a 1 back, it is turned on. As a test, turn it off by:

echo 0 > /proc/sys/net/ipv4/tcp_ecn

and see if the slow ping still happens.

BTW, Ian Gulliver wrote a useful program called ecncheck which tests ECN 
along a route. There is also a companion program called ecnmx which
compiles from the same tarball that does the same for mailservers. Look for
it on freshmeat.net


-- 
Jack Bowling
mailto: jbinpg at shaw.ca