Continually having to renew/flush DNS

I am having a very strange issue where my users lose connection to our terminal server and then we have to run the command "ipconfig /flushdns" once we do that it seems to fix it momentarily.  The issue is seemingly random and when it is occurring I can run "nslookup servername" and the server always resolves.  I can also always ping the servername IP address when this occurs.

This is running on a Server 2008 R2 virtualized server.

DNS event viewer is relatively clean, a few errors every few months but nothing that draws my attention.

One note:  We have several satellite offices that all VPN to a central office.  That is where our servers are located.  They are all on separate network subnets.  The DHCP DNS is set the same at each location.  I don't think this is a network issue, since I can always ping the servername and resolve the name with nslookup.

Thanks
LouisvilleGeekAsked:
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ManicDCommented:
try

 
ipconfig /displaydns >> c:\displaydns.txt

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and then review the output in the text file.

It might shed some light on what is occuring
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AnutechnologiesCommented:
Where does the DNS of the affected machine point?  Do you have two different DNS entries and are both resolving to the correct IP for the server?
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LouisvilleGeekAuthor Commented:
DNS on server NIC is correct.  They all point to the same 2 IP's.  I have disabled the DNS server on the secondary IP because I wanted to eliminate one from the problem in-case it was an issue with the replicating between the 2 servers.

manic, I will try that when the problem next occurs.
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AnutechnologiesCommented:
On the server, do the servers point back and forth to each other or to themselves?
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LouisvilleGeekAuthor Commented:
Anu,  DNS Server 1 has DNS Server 2 set as its primary and itself as its secondary.  I have disabled DNS on server 2 temporarly to eliminate that this is an issue with replication b/w both DNS servers.

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AnutechnologiesCommented:
Ok, that can be an issue.  Any Windows server that has DNS should only point to itself, otherwise you can corrupt the DNS.  Server 1 should only point to server 1 for DNS and server 2 should only point to server 2.  Try fixing that, restart both DNs services and see if it still happens.
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Craig BeckCommented:
I don't agree - using a DNS server for lookups will not exchange any data and therefore will not cause corruption.

Are you talking about Server1 using Server2 for DNS in the NIC or in DNS Management?  If you have configured this on the NIC it will only affect lookups from the server itself, and not from clients.  If you've done it in DNS Management via the Forwarders tab this won't cause too much of an issue, but it can be pointless if both servers are using failed forwarders.

I would check the DNS suffix is correct on your clients.  This can be assigned via DHCP, or manually on the NIC.
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AnutechnologiesCommented:
Actually I just looked it up.  While the primary DNS should point to itself, the secondary issue was resolved in a later update to 2003 and does not affect 2008, thus my suggestion does not apply to you.  this used to cause an issue with DNS lookups.
There are a few other things to look at:
  Is there a hosts. entry on the client for this server?  
  Was the server manually entered into DNS, and if so, did you reload the zone?
  Is Netbios or Wins enabled on the client?
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LouisvilleGeekAuthor Commented:
Craig,  The DNS suffix is set properly through DHCP.

Anu,

I have tried to create a hosts entry for testing but even with a hosts entry it doesn't work.  Or it will work for a while then stop working.  Very random.

I don't know if the server was manually entered into DNS or not.  How do you reload the zone?

Netbios is enabled no WINS.  If WINS is enabled we aren't using it.
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LouisvilleGeekAuthor Commented:
I just had the issue occur and I ran the /displaydns switch.  While most of the output looked normal there was definitley something abnormal there as well:

Anyone know what the think about that one?  The issue is resolved by flushing DNS several times.

 
servername.domain.local
    ----------------------------------------
    Name does not exist.

Open in new window

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AnutechnologiesCommented:
Probably not the issue, but make sure that udp port 53 is open through the VPN and on the server for DNS.  Also, try disabling Netbios on the system and see if that fixes it.
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LouisvilleGeekAuthor Commented:
Update: disabled netbios - no change,  tested UDP 53 traffic through the VPN and it passes through.

Found that I can resolve the issue (usually) with doing an ipconfig /flushdns.

What is really strange is I can remote desktop to the name of the terminal server - be connected in just fine, then all of a sudden the session starts getting really slow and laggy then it disconnects.  When I try to reconnect - no dice.  Says the terminal server can't be found.  Try to ping the name or FQDN and no dice.

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LouisvilleGeekAuthor Commented:
in my last post meant to say "ipconfig /renew" usually fixes the problem.


/flushdns does not always fix the issue.
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LouisvilleGeekAuthor Commented:
Question abandoned.  Closing.
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LouisvilleGeekAuthor Commented:
Question has been abandoned.
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