[Techtalk] sudden, strange DNS/server issues...

[Gayathri Swaminathan]

Hey Walt:

Replies inline

On Feb 19, 2008 7:30 AM, Walt <pippin at freeshell.org> wrote:

> Hi folks...
>
> Logged into the server and found that 'uptime' displayed
> a 1002.00 server load! I ran 'top' and it said that CPU use
> was at .2% and there didn't seem to be anything strange
> at the top of the list or anything utilizing much RAM.
> I don't know the command (if there is one) to monitor
> disk utilization, so it's possible that something could've
> been writing massively to disk.
>

For disk utilizations try iostats, this will give you precise io-wait,
read/writes etc.,


>
> At any rate, I rebooted the server, job app ran fine
> again, and all seemed to be well. However, ever
> since then our DNS resolution seems to be screwed
> up and painfully, extremely slow! I've been unable to
> find any cause for this. This system is a caching
> nameserver for a our network and handles some
> internal network name resolution. I've tried to changing
> its named delegation to OpenDNS and that makes no
> difference, but if I change an individual workstation to
> point to OpenDNS everything seems to work fine.
>

Sounds to me something wrong with the caching nameserver setup is acting up.
That is where you should start. Review /var/named/chroot/etc/named.conf  and
then "dig <domain name>" from server. Configure a client pointing it to the
caching-nameserver and see how long "dig <domain name>" takes there.




>
> A speedtest on http://speedtest.net shows 26 Mb, so
> our actual speed seems just fine.
>
>
For network connectivity/ bandwidth tests often use tools from here
http://www.internet2.edu/tools/

Download this Knoppix iso,
http://e2epi.internet2.edu/network-performance-toolkit.html

and you could either use NDT, OWAMP, NPAD for troubleshooting.

But your problem does not sound network connectivity related. More of a name
server issue.

-- 
Gayathri Swaminathan
gpgkey: 3EFB3D39
Volunteer, FDP