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Nslookup display

Posted on 2009-04-14
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Last Modified: 2012-05-06
Nslookup display

I am sitting at the DNS server 10.25.17.11 and issuing NSlookup and getting the following:

C:\Documents and Settings\XX.YYI>nslookup dc1.YYcom
*** Can't find server name for address 10.25.17.11: Non-existent domain
Server:  UnKnown
Address:  10.25.17.11

Name:    dc1.YY.com
Address:  10.25.17.11


can you tell where the issue is?

Thanks
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Question by:jskfan
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8 Comments
 
LVL 71

Accepted Solution

by:
Chris Dent earned 1000 total points
ID: 24137771

Essentially it means this request failed:

nslookup 10.25.17.11

Typically because either the Reverse Lookup Zone doesn't exist, or because no PTR record exists (in that Reverse Lookup Zone) for that IP address.

Chris
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Author Comment

by:jskfan
ID: 24137802
is it mandotory to have Reverse lookup zone and the PTR record in order to nslookup work properly?
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LVL 71

Expert Comment

by:Chris Dent
ID: 24137823

The error it throws should be considered a warning rather than a hard-error. It will still successfully lookup names (and IPs), but it will always fail the check when starting without both A and PTR records.

Chris
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LVL 27

Assisted Solution

by:bluntTony
bluntTony earned 1000 total points
ID: 24137935
Like Chris says, It's basically saying it couldn't resolve the DNS server IP address to a name, because it couldn't find the PTR record. Before performing your actual query, it will try to resolve the IP address of your preferred DNS server (set in your network connection config) to a name - this requires a reverse lookup. Your actual query return successfully (even though it was for the same machine, but a forward lookup instead).

Active Directory itself doesn't necessarily need reverse lookups to function correctly, although some network software may require them to exist. Nslookup is an example of some software which requires reverse lookups to function fully. You can resolve DNS names to IP addresses without reverse lookups, but not the other way. It is possible to actually live quite happily with reverse lookups in simple setups.

Have a read of this for more info on adding a reverse lookup zone: http://technet.microsoft.com/en-us/library/cc961414.aspx
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LVL 27

Expert Comment

by:bluntTony
ID: 24137950
It is possible to actually live quite happily without reverse lookups in simple setups.

-- sorry - typo...
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Author Comment

by:jskfan
ID: 24138187
so if I just type Nslookup by itself. it will take it as typing Nslookup IPaddress?
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LVL 71

Expert Comment

by:Chris Dent
ID: 24138203

If you run nslookup on it's own it will open the nslookup prompt. It's just nslookup, as a program, does two checks whenever you connect to a DNS server, it looks for the Host (A) record for the name, and the Pointer (PTR) record for the IP.

Chris
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Author Closing Comment

by:jskfan
ID: 31569877
thanks guys!!
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