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Inconsistent DNS Repsonse Timeouts

Tommy Brown
Respected Contributor

Inconsistent DNS Repsonse Timeouts

Hello All, I know this sounds vague. We are having problems resolving WWW.NOAA.GOV. Some times it is quick and sometimes it is so slow that we timeout waiting for response. To compound the issue, We have AD servers for the PC population and HPUX DNS servers for the non-windows side of the house. Both sides typically have no problems except for this one site. The Unix DNS servers have a 5 second time out with 4 retries. the AD has a 2 second timeout with 1 retry. I think that is the principal problem but no one wants to accept that. The calls for NOAA come from PC users. I saw in previous posts about Windows AD responding intermittently. Can that possibly be the case here? Thanks for you comments and suggestions.
Tommy
I may be slow, but I get there !
3 REPLIES
Dave Johnson_1
Super Advisor

Re: Inconsistent DNS Repsonse Timeouts

I have no trouble resolving www.noaa.gov the couple times I tried it on HPUX and Windows. On both systems the response was instant. Since I know this does not help much, here is our setup which is different from yours.
We do not really have DNS setup on the HPUX systems. We use NIS to keep the hosts file info. Each HPUX server does have a hosts file that only lists the HPUX servers. My nsswitch.conf file has this line in it:
hosts: files [NOTFOUND=continue UNAVAIL=continue] nis [NOTFOUND=continue UNAVAIL=continue] dns
and my resolv.conf file contains:
search buffetsinc.com
nameserver
nameserver

Here is the result of nslookup on HPUX:
# nslookup www.noaa.gov
Using /etc/hosts on: hpuxserver1

looking up FILES
Trying NIS
Trying DNS
Non-authoritative answer:
Name: hdq-woc.lb.noaa.gov
Addresses: 140.90.200.10, 140.90.33.10, 216.38.80.60
Aliases: www.noaa.gov

Here is the result of nslookup on Windows:
C:\>nslookup www.noaa.gov
Server: .buffetsinc.com
Address:

Non-authoritative answer:
Name: hdq-woc.lb.noaa.gov
Addresses: 140.90.200.10
216.38.80.60
140.90.33.10
Aliases: www.noaa.gov

Hope this helps,
-Dave
Tommy Brown
Respected Contributor

Re: Inconsistent DNS Repsonse Timeouts

Thanks, Dave. That is the same addresses that I receive. I requested the Windows Admins add some time to the timeout to see if it helps. I am not sure they have the latest root hints either..
Tommy
I may be slow, but I get there !
rick jones
Honored Contributor

Re: Inconsistent DNS Repsonse Timeouts

To be "certain" it is a question of slowness and not actual loss of the datagram carrying the request or response, you would probably need to take packet traces. Otherwise, one cannot really say if a timeout was simply because the upstream DNS server(s) were slow, or if the request or response were lost.
there is no rest for the wicked yet the virtuous have no pillows