Skip to main content

windows - DNS requests failing from computers that can ping DNS server

I have a situation where computers in some of our remote offices from time to time lose the ability to use our DNS server (in head office) to resolve hostnames. The offices are connected via VPN using Cisco ASA 5505 (VPNclient config rather than Site to Site) connecting back to an ASA 5510 at head office.



Ping to the IP address of the DNS server works. But nslookup will get a "no response from server" message. Computers in other locations can use DNS fine.



This is an intermittent problem. One day/hour it works, another it doesn't. Other offices connected in the same way work when another doesn't.



No config changes have been made on routers around the time we see the problem.



The DNS server that drops out for the clients is on our private address space in the 172.16.0.0/12 network. The ASA 5505s and the clients behind them are each in a 10.6.x.0/24 private address space.




Each ASA 5505 has its DHCP server configured to assign addresses and DNS config to clients behind them -these are generally Windows XP clients, with a growing number of Windows 7. The primary DNS is our one in the 172.16.0.0/12 space, the secondary is 8.8.8.8 to allow access to the internet in case the VPN tunnel drops for any reason.



Some users have reported that the problem goes away after doing a repair connection in Windows XP. I think this could be caused by the DNS cache being flushed as part of this - the Windows DNS cache makes the intermittent problem look less so because it caches failed lookups as well as successful ones. However, it is possible some other aspect of Windows is involved. Windows 7 clients have also had the same problem.



Any pointers on deeper troubleshooting, or anyone else found this?

Comments

Post a Comment

Popular posts from this blog

iLO 3 Firmware Update (HP Proliant DL380 G7)

The iLO web interface allows me to upload a .bin file ( Obtain the firmware image (.bin) file from the Online ROM Flash Component for HP Integrated Lights-Out. ) The iLO web interface redirects me to a page in the HP support website ( http://www.hp.com/go/iLO ) where I am supposed to find this .bin firmware, but no luck for me. The support website is a mess and very slow, badly categorized and generally unusable. Where can I find this .bin file? The only related link I am able to find asks me about my server operating system (what does this have to do with the iLO?!) and lets me download an .iso with no .bin file And also a related question: what is the latest iLO 3 version? (for Proliant DL380 G7, not sure if the iLO is tied to the server model)
Post a Comment
Read more

linux - Awstats - outputting stats for merged Access_logs only producing stats for one server's log

I've been attempting this for two weeks and I've accessed countless number of sites on this issue and it seems there is something I'm not getting here and I'm at a lost. I manged to figure out how to merge logs from two servers together. (Taking care to only merge the matching domains together) The logs from the first server span from 15 Dec 2012 to 8 April 2014 The logs from the second server span from 2 Mar 2014 to 9 April 2014 I was able to successfully merge them using the logresolvemerge.pl script simply enermerating each log and > out_putting_it_to_file Looking at the two logs from each server the format seems exactly the same. The problem I'm having is producing the stats page for the logs. The command I've boiled it down to is /usr/share/awstats/tools/awstats_buildstaticpages.pl -configdir=/home/User/Documents/conf/ -config=example.com awstatsprog=/usr/share/awstats/wwwroot/cgi-bin/awstats.pl dir=/home/User/Documents/parced -month=all -year=all...
Post a Comment
Read more

linux - How can I get my mediawiki to stop thinking I have cookies disabled?

I've searched half a day for how to resolve this issue, and can't figure it out. Shortly after I made my wiki a simple private wiki according to the instructions at Mediawiki's website, it started giving me this weird login error message: Wiki uses cookies to log in users. You have cookies disabled. Please enable them and try again. If I remove those private wiki settings, the error disappears, even if I try logging in. But I need it to be a private wiki for only my team. So what do I do? Here's what I've done so far. Just to be safe, after ever change, I try rebooting Apache using: sudo /etc/init.d/apache2 restart In my php.ini file, I have the following set: session.save_path = "/var/lib/php5" session.cookie_secure = secure session.cookie_path = /tmp session.cookie_domain = my server's internal URL (should I even set this? this field was blank before, but not commented out) session.referer_check = Off I ran the following to ensure that the fold...
Post a Comment
Read more