# Internal DNS not resolving all the time



## aasmith26 (Nov 28, 2008)

My win2003 server is set up for internal DNS resolution. Every once in a while when I try to navigate to an internal website (i.e..subdomain.domain.com), the name will not resolve. However, if I manually enter the IP Address into the address bar it works fine. 

If I flush the DNS Cache and Re-Register w/ DNS, it usually fixes the problem, but not all the time. 

What might be causing this problem? Flushing is becoming a real pain in the rear.

Would something with WINS cause this to fail? It's very intermittent. 

Thanks for any help.


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## aasmith26 (Nov 28, 2008)

Anyone? lol


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## avisitor (Jul 13, 2008)

I assume you're trying to access it by FQDN, right?


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## aasmith26 (Nov 28, 2008)

Sure thing....meaning by typing subdomain.domain.com... of course.

**edit**

Checked eventvwr today and it seemed like the net logon service is losing connections with the domain controller constantly...weird...


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## avisitor (Jul 13, 2008)

They're probably related problems. AD is highly reliant on DNS resolution.

When this problem happens what happens when you run nslookup for that domain name.


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## aasmith26 (Nov 28, 2008)

cpdc01 is my DC...contains DNS, WINS and DHCP. It's the only DC.

Output of nslookup

Default Server: cpdc01.domain.com
Address: 192.168.0.30

>


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## Rockn (Jul 29, 2001)

Have you also set up reverse DNS? What is the TTL for the records? Is scavenging set up to purge old records? Have you created an A record for the internal web site?


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## aasmith26 (Nov 28, 2008)

TTL=64, and not sure how to set it up to scavenge/purge old records. Is that through WINS?


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## Rockn (Jul 29, 2001)

No, there is an option in DNS to scavenge stale records. You need to set it up at the server level and the zone level. In DNS right click the server name and go to properties and on the advanced tab check the scavenging check box. The default settings are fine for a small network. Next scroll down to your forward lookup zone and go to your domain.whatever zone, right click it and select properties. Click the aging button and check the box. Default settings are fine.

You never stated whether or not you set up a reverse lookup zone or not. Also, is there more than one AD/DNS server on your network and if so is replication working properly?


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## apr911 (Jan 26, 2007)

Are you flusing the DNS Cache on the DNS Server, the local host or the remote server?

It sounds like the host is not honoring the TTL but then, the page shouldnt be moving IPs so that should really matter either. On the other hand, if you are running flush dns and re-register with DNS on the remote server, the simplest fix would be to add a static A record to your DNS server and not rely on the auto register.

Next time the page becomes non-responsive, try doing a ping to the page and confirm the IP address.

For programs that make calls to DNS (ping, browser, FTP, email), DNS is supposed to work like this:
1. Check hostname (see if it is itself)
2. Check local DNS cache
3. Check local hosts file
4. Check DNS server.

If all of those fail, it fails over to the process used by NetBios Applications (Net Use, Net View, UNC paths, Network Neightborhood). This process goes as follows:

1. Local NB Cache (Local WINS Cache)
2. WINS Server
3. Broadcast
4. Local LMHosts file


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