Intermittent connection problem

[Colin Stefani]

Here's what I'd check first...

You mentioned that nslookup seems to "seldom" work between the sites. I am
wondering if there's any packet filtering/firewall setup in between the
sites? Are those sites directly connected (as in Frame-relay,
point-to-point, etc.)?

I didn't notice you say that you have administrative control of the other
side's DNS server, if not, both admins (yours and theirs) may want to check
the logs that named puts out to see if there's a configuration error in one
of the zone files, especially on the AIX box (hopefully you've done this
already). If one of the sides is rejecting a zone file then that could cause
it to not work properly, which might explain intermittency, as the secondary
may or may not be giving the right information.

Also, check /etc/named.conf (or .boot depending) to see if there's any
limitations on queries that are set.

I still think it sounds like port 53 is being blocked somewhere. Does the
AIX running (4 or 8 versions) have the ability to resolve hosts otherwise?
is it just this one network? The reason I ask is that, I'm wondering if it
can get to the root servers to determine who to ask for that domain? It's
just a hunch but worth checking out.

regards,

colin

 

-----Original Message-----
From: Morris M M Law
To: comp-protocols-dns-bind at moderators.isc.org
Sent: 12/13/00 10:38 AM
Subject: Intermittent connection problem

Dear DNS experts,

Our University (hkbu.edu.hk) are having intermittent connection problem
with 
Salzburg University (sbg.ac.at) and other Univ. in Austria.  I suspected
that 
the problem is related to the DNS configuration.  E-mail transfer is
affected 
and often returns error such as 'host name lookup failure' or 'name
server 
timeout'.  

Several tests has been done.

nslookup query from one of the nameserver (158.182.11.1) running AIX
named4 
in our University can seldom resolve the web server of Salzburg
University 
(www.sbg.ac.at).  
Bind8 run on AIX has been tested and also failed similarly.  
However, bind8 run on Linux (158.182.11.4) has been tested and always
succeed
in resolving sbg.ac.at. 
nslookup query from nameserver in sbg.ac.at (dsbgpx.edvz.sbg.ac.at) can 
only resolve the two nameservers in our University (ctsc.hkbu.edu.hk)
and
(net2.hkbu.edu.hk) but failed to resolve all other host in our site.

It sounds that this is not a network problem since ping to IP address
always
work.  But how to describe and solve the problem?

E-mail reply or posting are much appreciated.

-- 
Morris Law
Assistant Computer Officer    Address : 224 Waterloo Road, KLN, Hong
Kong
Science Faculty               Tel : (852) 23395909   Fax : (852)
23395862
Hong Kong Baptist University  WWW : http://www.sci.hkbu.edu.hk/~morris
Email : morris at hkbu.edu.hk  or  morrismmlaw at yahoo.com       ICQ :
6380626
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