[PLUG] DNS issues

[Paul Heinlein]

On 5/11/05 1:55 PM, Ovid wrote:
> Hi all,
> 
> When I first set up my DSL through Earthlink, I discovered that my DNS
> resolution was very, very slow.  Earthlink wouldn't help me because I
> was running FC2.  A friend sent me a list of nameserver IP addresses to
>  add to my /etc/resolv.conf and that fixed the problem.

You might try disabling IPv6; that seems to do it for some:

echo "alias ipv6 off" >> /etc/modules.conf

I don't know if a reboot is necessary, but you almost certainly have to 
restart networking: /etc/init.d/network restart

> How the heck do I diagnose issues like this?  More importantly, any
> pointers on fixing them?

strace and tcpdump are your two biggest friends when an application is 
misbehaving. In this case, the tcpdump solution might provide more 
interesting feedback.

In xterm #1, do (as root)

   tcpdump port 53

In xterm #2, do

   dig www.pdxlinux.org

The console spew will tell you what servers your resolver library is 
trying to use; the timestamps will tell you where the delay is happening 
(if you can't spot it during the run).

-- 
Paul Heinlein <> heinlein at madboa.com <> www.madboa.com