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We have the following problem with our Windows AD DNS Servers which is in turn causing intermittent issues on our clients:

On one of our AD DC/DNS servers (Pluto) 2k3R2, we can ping an internal based host using it's full external hostname (docs.is.com.au) and it will resolve back to 192.168.1.210 and reply to pings - great!

On another AD DC/DNS server (Venus) 2k8R2, we ping the same hostname and it resolves to it's external internet address of 203.2.3.4 and cannot be pinged due to the firewall doing what it is meant to do and blocking it.

On both servers, if I was to ping docs (without the full domain name) it resolves to the correct internal IP address.

Why would one DNS Server be finding the internal IP correctly and the other not and resolving to the External IP?

Some background:

Our AD Domain: im.is.com.au Inside of this forward lookup zone the name docs is a CNAME pointing to sharepoint.im.is.com.au
We also have a forward lookup zone of is.com.au in which docs is a CNAME also pointing to sharepoint.im.is.com.au

Doing an NSLookup on Venus the host that does not give the correct ping address results in the following:

>nslookup docs.is.com.au venus
1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa
    primary name server = cha-na.telstra.net
    responsible mail addr = root.cha-na.telstra.net
    serial  = 20081105
    refresh = 3600 (1 hour)
    retry   = 900 (15 mins)
    expire  = 3600000 (41 days 16 hours)
    default TTL = 3600 (1 hour)

Server:  UnKnown
Address:  ::1

Name:    sharepoint.im.is.com.au
Address:  192.168.1.210
Aliases:  docs.im.is.com.au

Doing a NSLookup on Pluto which does give the correct address:

>nslookup docs.is.com.au pluto

Server:  pluto.im.is.com.au
Address:  192.168.1.220

Name:    sharepoint.im.is.com.au
Address:  192.168.1.210
Aliases:  docs.is.com.au

It seems like this second forward lookup zone is the problem but I am not sure how or where I should be looking.

If any more info is required, please let me know!

EDIT:

Similar posting here: Windows Server 2008 - Strange DNS resolution between clients and server but the clients and servers are all using internal AD DNS servers, no external DNS Servers are setup on the nics.

Both AD DNS servers have ISP name servers setup in the Forwarders tab with 'Use root hints' UNCHECKED.
The servers do not have any ISP/Google/Other external DNS Servers listed on their network adapters, nor do the clients - they are all pointing to the internal servers or in the case of the DNS Servers are uisng 127.0.0.1 as their alternates.

EDIT 2:

Results of NSLookup on client - after possible fix implemented (see comments)

>nslookup docs.im.com.au venus
Server:  venus.im.is.com.au
Address:  192.168.1.217

Name:    sharepoint.im.is.com.au
Address:  192.168.1.210
Aliases:  docs.is.com.au

>nslookup docs.is.com.au pluto
Server:  pluto.im.is.com.au
Address:  192.168.1.220

Name:    sharepoint.im.is.com.au
Address:  192.168.1.210
Aliases:  docs.is.com.au
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You should check your DNS configuration. Open the DNS management console, expand server node, right-click conditional forwarders node and select the current conditional forwarder. Compare these configuration between the two Win2k servers. Type the domain name of the zone you want to resolve to (docs.is.com.au) and provide the IP address of the DNS server responsible for docs.is.com.au. I already saw technicians configured the IP of docs instead of the DNS which is responsible for it.

Also , it looks like your AD DNS server venus doesn't know the server name - venus - which you are requesting.

Server: UnKnown Address: ::1

This might be because it's the name of the server and your DNS is listening only on IPv4. First you should solve this issue. You didn't provide information from the client and only from the servers as I understand. You should also check from an external client , not from the actual Win2k(3/8) servers.

It seems that the Win2k8r2 is configured with IPv6 while Win2k3 IPv6 is very limited. So additionally I would close (if possible) IPv6 on Win2k8r2.

  • Hi Daniel, I have removed IPV6 from the 2k8r2 server however doing a NSLookup directly on it still has the same result as above. Found that another DNS server is in play (not setup by me) which did not have the is.com.au Forward Lookup Zone which I believe is the culprit of the posted fault. Have added it and will monitor the results over the next couple of days. No Conditional Forwarders found. Thank you – user1693454 Sep 3 '14 at 4:42

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