[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: queer dns access problem



-----Original Message-----
From: redhat-list-bounces redhat com
[mailto:redhat-list-bounces redhat com] On Behalf Of Bill Tangren
Sent: Monday, December 10, 2007 9:01 AM
To: redhat-list redhat com
Subject: queer dns access problem

I have two servers that are set up in the same way, except that the one
that is working properly is running RHEL ES 4.6 while the other is
running
4.5. I can't update the latter, because DNS is not working properly.
Ordinarily I would poke around until I found the problem, and not bother
y'all, but I'm stumped as to what the problem could be. Except for MAC
address and IP number, the /etc/hosts, /etc/sysconfig/network,
/etc/resolv.conf, and /etc/sysconfig/network-scripts/ifcfg-eth0 files
are
identical. Neither run a DNS service. Both are on the same subnet. Both
boxes are running iptables, but turning off iptables doesn't help. I can
ssh into, and ping the broken box. I can ssh out of that box too, if I
use
ip numbers. When I try to do an nslookup on the broken box, all I get
is:

;; connection timed out; no servers could be reached.

Could someone give me a few clues as to where to look to diagnose this
problem?


Some ideas:

Turn off firewalling if possible.

Check default route
# ip route list
10.212.166.0/24 dev eth0  proto kernel  scope link  src 10.212.166.26
169.254.0.0/16 dev eth0  scope link
default via 10.212.166.1 dev eth0 <----!!!!

correct if necessary.

Check for UDP connectivity

# nmap -PU -p53 DNS.SERVER.IP.ADDRESS

# traceroute -U DNS.SERVER.IP.ADDRESS

If either works then check for an access list on your DNS. Usually in named.conf

Try a different switch port if possible.

--
Stephen Carville <scarville landam com>
Systems Engineer
Land America
1.626.667.1450 X1326
#####################################################################
Ad eundum quo nemo ante iit.



[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]