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nslookup server unknown, dns problem ?

Posted on 2011-03-09
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Last Modified: 2012-06-27
Hi Experts,
 
I have got as simple networking question. In my Windows 2008 Domain, DNS is installed
on a Win2008 Server called kos.
 
FQDN : kos.mydomain.local
 
When I am connected to that Domain on a client (AD), start a command window and
issue a nslookup command... it says the StandardServer is unknown ?!
 
 
C:\>nslookup
Standardserver:  UnKnown
Address:  192.168.0.5
> maui
Server:  UnKnown
Address:  192.168.0.5

Name:    maui.mydomain.local
Address:  192.168.0.71

Open in new window


WHY, in the DNS Settings the DNS-Server is configuered ?!
 
Thanks in Advance
 
Hansjoerg
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Question by:hgraesslin1
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5 Comments
 
LVL 13

Expert Comment

by:AustinComputerLabs
ID: 35086181
I have no issues on my 2008 server and I recieve the same return.

C:\Users\RAD.ACL>nslookup
Default Server:  UnKno
Address:  192.168.0.25

> acl1
Server:  UnKnown
Address:  192.168.0.25

Name:    acl1.ACL.Corp
Address:  192.168.0.25
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Expert Comment

by:Darius Ghassem
ID: 35086194
Do you have a reverse lookup zone in DNS? If you don't then create one.
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LVL 13

Assisted Solution

by:AustinComputerLabs
AustinComputerLabs earned 2000 total points
ID: 35086217
Like dariusg syas:

If reverse DNS for that IP address is not setup correctly, then NSLOOKUP cannot determine the name associated with the IP address.
On Windows Vista/2008, it then says "Default Server: UnKnown".
On earlier Windows versions, it displays the error message "*** Can't find server name for address ...".

This does NOT indicate a problem with the actual domain name that you are trying to look up.
It only means that there is no reverse DNS name for the DNS server IP address, which in most cases may not be a problem at all.

To fix this you need to properly configure the reverse zone for the IP address of the DNS server, and make sure that the reverse zone is properly delegated to the server by your IP provider. See the reference article below for more details.

To create a reverse zone in Simple DNS Plus, click the "Records" button, select "New" -> "Zone", select "Reverse Zone...", and follow the prompts.

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Author Comment

by:hgraesslin1
ID: 35087814
Could you tell me what is a reverse zone, I saw this in the DNS of the Server.

For my understanding DNS is a mapping between hostnames in a Domain (fqdn) and IP Adresses, but why do you need a reverse zone... , because this mapping is exact in both ways.

Thx for your responses...

Hansjoerg
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Accepted Solution

by:
AustinComputerLabs earned 2000 total points
ID: 35090197
A forward zone converts a name into an IP address.
A reverse zone converts an IP address into a name.

From MS:
Testing for Reverse Lookup Zones and PTR Resource Records
You do not need reverse lookup zones and PTR resource records for Active Directory to function. However, you need them if you want clients to be able to resolve FQDNs from IP addresses. Also, PTR resource records are commonly used by some applications for security purposes, to verify the identity of the client.

You do not need to have the reverse lookup zones and PTR resource records on your own servers; instead, another DNS server can contain these zones.

After you have configured your reverse lookup zones and PTR resource records, manually examine them in the DNS console. A reverse lookup zone must exist for each subnet, and the parent reverse lookup zone must have a delegation to your reverse lookup zone. For example, if you have a private root and the subnets 172.32.16.x and 172.32.17.x, the private root can host all reverse lookup zones, or it can contain the reverse lookup zone 172.32.x and delegate the reverse lookup zones 172.32.16.x and 172.32.17.x to other servers. Also, PTR resource records must exist for all the computers in your network. For more information about adding a reverse lookup zone, see "Adding a Reverse Lookup Zone" earlier in this chapter.

You can also use Nslookup to verify that the reverse lookup zones and PTR resource records are configured correctly.

To make sure your reverse lookup zones and PTR resource records are configured correctly

1.Start Nslookup by typing Nslookup at the command prompt and then pressing ENTER.

2.Switch to the server you want to query by typing the following:
server < Server IP Address > 

3.Enter the IP address of the computer whose PTR resource record you want to verify, and then press ENTER.
If the reverse lookup zone and PTR resource record are configured correctly, Nslookup returns the name of the computer.

4.To quit Nslookup, type exit and then press ENTER.

http://technet.microsoft.com/en-us/library/cc959303.aspx
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