Name resolution problems?

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Name resolution problems?

Postposted on Mon Aug 16, 2010 9:53 pm

A week ago I opened a vpn to a remote location, while another vpn connection (to a separate, second location) was still open. The name resolving has been messed up since. I've uninstalled both VPNs on my machine, and reinstalled my ethernet driver.

When I try to ping any other computer in my house called (eg, 'Bobbie'), it says "Pinging Bobbie.ou.edu [72.215.225.9] with 32 bytes of data". But I'm not connected to the OU vpn and that address is actually for my cable/internet provider. The ping times out when I use IPv4. But when I ping with IPv6, (ie, "Ping Bobbie -6"), things work fine.

This problem is restricted to by main computer. Other Windows and Linux machines have always been able to resolve each other names. Any ideas how to fix this or where I should look next?
Edit: changed title from 'DHCP problems?'
Last edited by wibeasley on Mon Aug 16, 2010 11:17 pm, edited 1 time in total.
wibeasley
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Re: DHCP problems?

Postposted on Mon Aug 16, 2010 10:21 pm

Since your other WIndows and Linux machines are able to resolve each other successfully, you can probably eliminate the DHCP assigned DNS servers from your router as the root cause. (assuming there is one in your network).
XP (also an assumption) should be expiring the entries in the DNS cache after 24 hours, however you can flush it anyways with ipconfig /flushdns. Assuming they're on the same subnet, you might want to also delete your arp entries via arp -d *
Does your VPN software temporarily add anything to your hosts file? Have you checked that?
Also, under your IP settings, is your connection set manually to append the DNS suffix from a list (i.e. the first entry being ou.edu? In other words is it set to "Append primary and connection specific DNS suffixes" or "Append these DNS suffixes (in order)"?
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Re: Name resolution problems?

Postposted on Mon Aug 16, 2010 11:55 pm

I have flushed the dns and have run "arp -d *", without success. I see 'ou.edu' listed first in the 'DNS Suffix Search List' when I run 'ipconfig /all'. Is that supproting the issue in your last sentence?

I'm running Vista Business x64. I see it listed in the registry "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\SearchList". I've deleted those entries "ou.edu" and "ok.cox.net" and am rebooting now.
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Re: Name resolution problems?

Postposted on Tue Aug 17, 2010 12:07 am

Thank you unkoil -everything seems to be working well.

Is that common for vpn software to add that stuff to the registry? Seems like a hack to me.
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Re: Name resolution problems?

Postposted on Tue Aug 17, 2010 12:09 am

Yes that does support my last statement.
Since ou.edu was the first in the list, when you pinged bobbie (for example) it automatically appended ou.edu as the dns suffix, giving you the fqdn of bobbie.ou.edu
If the reg modification and reboot didn't help, can you go into network properties --> Internet protocol 4 -- > properties --> advanced --> DNS tab and check "append primary and connection specific DNS suffixes" and try it again?
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Re: Name resolution problems?

Postposted on Tue Aug 17, 2010 12:12 am

it worked? hah, score!
yeah, i've seen VPN software do that all the time, though it will usually revert itself back to your settings once you disconnect. Reason being that once you are VPN-ed into the system, you might be sitting on a DNS domain that is only resolvable from inside the network.
Two VPN connections at once might have confused the settings.
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Re: Name resolution problems?

Postposted on Tue Aug 17, 2010 12:19 am

Seems like there could be a more robust way to do that ...especially if the VPN didn't revert its setting after being uninstalled.

Whatever. Thanks again for your quick help.
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