On Sat, 12 Feb 2011 14:35:51 +0100, Aram Avetisyan
<[log in to unmask]> wrote:

>Hello,
>
>Using SL 5.4 ( 2.6.18-194.32.1.el5 ) from my apartment results in very
>slow DNS lookups -- on the order of 30 seconds for each new page. I am
>pretty sure the problem is with DNS because it goes away if I use vpnc
>to tunnel to Fermilab. Google led me to the following workaround: add
>
>alias ipv6 off
>alias net-pf-10 off
>
>to /etc/modprobe.conf . This works, but the system now complains about
>some error with ipv6 tables when it boots. Is there a better way to fix
>this (without changing any router settings -- I don't have the password)
?
>
>Thanks.
>
>-- Aram

The advice at
http://wiki.centos.org/FAQ/CentOS5#head-47912ebdae3b5ac10ff76053ef057c366
b421dc4
(that's all one line) worked for me.  In particular running "/sbin/chkcon
fig
ip6tables off", once there is no ipv6 traffic for the ip6tables firewall 
to
protect.

HTH,

Stephen Isard