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NSLookup appending parent suffixes in Active Directory

Posted on 2008-09-29
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Last Modified: 2011-09-20
In the past week we've noticed that all our NSLookups are appending the parents domain suffixes for example:
"NSLookup server.domain.net.nz" :- returns

Server: domaincontroller.domain.net.nz
Address: 10.x.x.x

Non-authoritative answer:
Name: server.domain.net.nz.net.nz
Address: 202.xx.xx.xx

The 202.xx.xx.xx.xx Address actually belongs to nz.net.nz, which is nothing to do with our company.

Now this has just started happening all the IT Admins swear they haven't changed anything and there have been no other known changes.  One of our IT Admins has an Active Directory Setup at home and he's also having the same problems.  We know we can apply a fix for this automatically via Group Policy and/or manually via TCP/IP (Advanced - DNS) Properties, by changing the "Append these DNS suffixes (in order)":.  But the question is why has it started happening all of a sudden and is it possible to change it, without going through Group Policy or TCP/IP Properties.

Cheers
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Question by:matrixnz
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Expert Comment

by:cheeselover73
ID: 22603750
A little dot at the and could help:

nslookup server.domain.net.nz.     <- end with dot
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Author Comment

by:matrixnz
ID: 22603789
Hi cheeselover73

Thanks for the response, yes the period at the end also works, however my main objective is to figure out why all of sudden it changed, as no period was required previously.

Cheers
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Expert Comment

by:cheeselover73
ID: 22612900
can you paste ipconfig /all
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Author Comment

by:matrixnz
ID: 22613107
Windows IP Configuration
        Host Name . . . . . . . . . . . . : XXX-X-XXXXXX
        Primary Dns Suffix  . . . . . . . : domain.net.nz
        Node Type . . . . . . . . . . . . : Hybrid
        IP Routing Enabled. . . . . . . . : No
        WINS Proxy Enabled. . . . . . . . : No
        DNS Suffix Search List. . . . . . : domain.net.nz
                                            DOMAIN.NET.NZ
                                            net.nz
Ethernet adapter Local Area Connection:
        Connection-specific DNS Suffix  . : domain.net.nz
        Description . . . . . . . . . . . : Broadcom NetXtreme 57xx Gigabit Controller
        Physical Address. . . . . . . . . : XX-XX-XX-XX-XX-XX
        Dhcp Enabled. . . . . . . . . . . : Yes
        Autoconfiguration Enabled . . . . : Yes
        IP Address. . . . . . . . . . . . : 10.2.1.22
        Subnet Mask . . . . . . . . . . . : 255.255.0.0
        Default Gateway . . . . . . . . . : 10.2.255.254
        DHCP Server . . . . . . . . . . . : 10.2.1.1
        DNS Servers . . . . . . . . . . . : 10.2.1.1
                                            10.1.1.1
        Primary WINS Server . . . . . . . : 10.1.1.1
        Lease Obtained. . . . . . . . . . : Tuesday, 30 September 2008 3:43:05 p.m.
        Lease Expires . . . . . . . . . . : Wednesday, 8 October 2008 3:43:05 p.m.
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Accepted Solution

by:
cheeselover73 earned 500 total points
ID: 22613738
This could be explanation:

If you enable debug mode in nslookup ("set d2"), you will notice that nslookup always FIRST appends dns suffix. When you try "nslookup server.domain.net.nz", and the suffix is domain.net.nz, it will first check "server.domain.net.nz.domain.net.nz". If it does not resolve it (and in this case it probably doesn't), it will try with parent suffix net.nz: "server.domain.net.nz.net.nz". Only if it doesn't resolve this (and all subsequent parent suffixes, if any) it will try without suffix.
What happened probably is that DNS server admin of nz.net.nz domain has set his server to respond with default IP address if host is not found. You can check this by trying anything.anything.nz.net.nz, it should resolve as same ip address.
If you try "nslookup server.domain.net", without .nz, you will get correct result if domain net.net.nz does not exist...". Turn on debug mode and it should explain itself :)
And don't worry, when you surf the net, dns lookup does not go in that order, it will first check same as you typed so there will not be unnecessary traffic.
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