topic Re: DNS issue. in Operating System - HP-UX

DNS issue.

kpatel786 — Tue, 01 Mar 2011 16:21:21 GMT

We have added on HPUX 11.11 server a new DNS server entry (windows 2003) in /etc/resolv.conf file.

We are able to ping the server:
(hqb) [SU] # ping 10.5.3.180
PING 10.5.3.180: 64 byte packets
64 bytes from 10.5.3.180: icmp_seq=0. time=0. ms
64 bytes from 10.5.3.180: icmp_seq=1. time=0. ms
64 bytes from 10.5.3.180: icmp_seq=2. time=0. ms
64 bytes from 10.5.3.180: icmp_seq=3. time=0. ms
64 bytes from 10.5.3.180: icmp_seq=4. time=0. ms
64 bytes from 10.5.3.180: icmp_seq=5. time=0. ms
64 bytes from 10.5.3.180: icmp_seq=6. time=0. ms

----10.5.3.180 PING Statistics----
7 packets transmitted, 7 packets received, 0% packet loss
round-trip (ms) min/avg/max = 0/0/0

But the nslookup is not able to resolve the the dns server name.

(hqb) [SU] # nslookup hpi.dhq.lr.org
*** Can't find server name for address 10.5.3.180: Non-existent domain
*** Default servers are not available
Using /etc/hosts on: hqb

looking up FILES
Trying DNS
*** can't find hpi.dhq.lr.org: No response from server

The same ip is getting resolved for other Linux and windows servers withing our network, however the same is failing for all the hpux boxes. Kindly provide suggestion/inputs to resolve the same. Thanking you in advance.

Re: DNS issue.

Jose Mosquera — Tue, 01 Mar 2011 16:38:27 GMT

Hi,

What is the content of /etc/resolv.conf file?

Rgds.

Re: DNS issue.

kpatel786 — Tue, 01 Mar 2011 16:40:40 GMT

(hqb) [SU] # more /etc/resolv.conf
search internal.lr.org dhq.lr.org lr.org
nameserver 10.5.3.180

Re: DNS issue.

Jose Mosquera — Tue, 01 Mar 2011 16:46:30 GMT

Hi,

Add this first line:
domain

Rgds

Re: DNS issue.

kpatel786 — Tue, 01 Mar 2011 16:51:23 GMT

(hqb) [SU] # more /etc/resolv.conf
search internal.lr.org dhq.lr.org lr.org
domain 10.5.3.180
===

[SU] # nslookup hpi.dhq.lr.org
Using /etc/hosts on: hqb

looking up FILES
Trying DNS
*** can't find hpi.dhq.lr.org: No response from server

Getting the above output.

Re: DNS issue.

Jose Mosquera — Tue, 01 Mar 2011 16:55:39 GMT

Nop!

/etc/etc/resolv.conf:
domain
search internal.lr.org dhq.lr.org lr.org
nameserver 10.5.3.180

Also, What is the content of /etc/nsswitch.conf file?

Rgds.

Re: DNS issue.

kpatel786 — Tue, 01 Mar 2011 16:57:24 GMT

(hqb) [SU] # more /etc/nsswitch.conf
#
# /etc/nsswitch.conf
#
# This file is for use on systems that are not running DNS or NIS.
#
# In this case we request that the resolver looks in local files only.
#
# See the Adminstering Internet Services Manual and the switch(4) man
# page for more information on the name service switch.
#

hosts: files [NOTFOUND=continue] dns

Re: DNS issue.

kpatel786 — Tue, 01 Mar 2011 17:17:17 GMT

Have tried putting the entries as you said, but the same is not working.

Re: DNS issue.

Jim Walls — Tue, 01 Mar 2011 21:45:23 GMT

Do you know if there is, in fact, and entry in the dns (located at 10.5.3.180) for the hostname hpi.dhq.lr.org ?

Re: DNS issue.

Jim Walls — Tue, 01 Mar 2011 21:56:22 GMT

Also:
>>>[SU] # nslookup hpi.dhq.lr.org
>>>Using /etc/hosts on: hqb
>>>
>>>looking up FILES
>>>Trying DNS
>>>*** can't find hpi.dhq.lr.org: No response from server

Check with your Network administrator to see that UDP port 53 (domain) is not blocked by a firewall rule.

Re: DNS issue.

Bill Hassell — Wed, 02 Mar 2011 00:28:38 GMT

> nslookup hpi.dhq.lr.org
> *** Can't find server name for address 10.5.3.180: Non-existent domain

So this indicates that the DNS nameserver can't even identify itself. nslookup has a nifty feature: You can specify any DNS server on the command line to override nsswitch.conf and resolv.conf:

nslookup hpi.dhq.lr.org 10.5.3.180

You'll likely get the same results but it does allow you to test other DNS servers on the command line. Another useful tool is nsquery:

nsquery hosts hpi.dhq.lr.org

This gives you a step-by-step report of the attempts to resolve the name and the results.

Since you can ping the DNS server yet it does not respond to DNS requests, the port is blocked *OR* you may have subnet mask or route error that is not setup for a valid return path. Do you have multiple LAN cards on this server? nettl (HP-UX trace) or Wireshark (PC based packet trace) may help.

Re: DNS issue.

Jose Mosquera — Wed, 02 Mar 2011 09:25:30 GMT

Hi again,

Please comment your current "host:" line and set this one:

hosts: files [NOTFOUND=continue UNAVAIL=continue TRYAGAIN=continue] dns [NOTFOUND=continue UNAVAIL=continue TRYAGAIN=return]

And please let me know the current domain definition set at /etc/etc/resolv.conf file.

Rgds.

Re: DNS issue.

kpatel786 — Wed, 02 Mar 2011 11:26:06 GMT

Thanks all the issue has been resolved. It was related to DNS PTR records at the window servers end.

Re: DNS issue.

kpatel786 — Wed, 02 Mar 2011 11:28:04 GMT

Thanks all for your time and assistance.