Big thanks and problem solved.

It took a while but after 35 for "DNS and BIND, 5th Edition" book and
some more searching. I located some information about "packet-filtering
firewalls that are configured to allow nameserver-to-nameserver traffic
but not resolver-to-nameserver traffic, because they typically expect
nameserver-to-nameserver traffic to originate from port 53 and terminate
at port 53"

Anyway, with this information I could force the people who maintain our
firewall (if we looked after it our-selfs we could have solved this
problem weeks ago!) to look into it and after another 3 weeks they came
back to me telling me that a lot of traffic was being blocked.

I useful site is http://194.242.112.64/~willemijns/dns.htm which gives a
list of open name servers which I could test our site on.

Hopefully all is well and thanks for all who helped.

Andrew


Andrew Watkins wrote:
> I am still trying to fix a problem where some users round the world who
> can not get an IP address for our server. http://www.lkl.ac.uk
>
> I have checked and our DNS seems to be working correctly. (i have tested
> on many DNS web sites. i.e. www.dnsstuff.com)
>
> I have tried a few open name-servers and I some times get the following
> error:
>
> nslookup
> > server 202.12.233.10

>
> > www.lkl.ac.uk.

> Server: ns.ntcif.telstra.com.au
> Address: 202.12.233.10
>
> *** ns.ntcif.telstra.com.au can't find www.lkl.ac.uk.: No response from
> server
> >

>
> but if I try another lookup on another address:
>
> > www.dcs.bbk.ac.uk.

> Server: ns.ntcif.telstra.com.au
> Address: 202.12.233.10
>
> Name: rhea.dcs.bbk.ac.uk
> Address: 193.61.29.2
> Aliases: www.dcs.bbk.ac.uk
>
> Any pointers.....
>
> Andrew
> PS.
> One think to note:
>
> The address 193.61.29.33 is registered under 2 different domains:
> dcs.bbk.ac.uk. and lkl.ac.uk.
>
> Thats is why I have set up a CNAME
> www.lkl.ac.uk => thor.dcs.bbk.ac.uk => 193.61.29.33
>
>