NSLOOKUP: *** Can't find server name... / Default Server: UnKnown

NSLOOKUP is a command line tool which comes with most operating systems and is used for querying DNS servers.

When NSLOOKUP starts, before anything else, it checks the computer's network configuration to determine the IP address of the DNS server that the computer uses.
Then it does a reverse DNS lookup on that IP address to determine the name of the DNS server.

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.

Related KB articles:

 Comments
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20 Feb 2019 13:32 UTC
yagnakanth
i can ping the ip , but i cant see the dns of the same ip by using nslookup
JH Software
2 Mar 2019 13:18 UTC
JH Software
I am sorry, but I do not understand your question. Could you perhaps e-mail us (support at jhsoftware.dk) with an example or more details?
Gravatar
27 Feb 2019 11:15 UTC
user
Hi,
Im using Simple DNS Plus as resolver but pages not opening correctly and when I try nslookup getting timeout error as below, I can ping dns max 5ms but while resolve its so late. I test with 8.8.8.8 but there is no problem also ping to 8.8.8.8 is 60ms what can be the problem at me ?
here nslookup result;

C:\Users\PC>nslookup google.com
DNS request timed out.
timeout was 2 seconds.
Server: UnKnown
Address: 172.16.57.154

Non-authoritative answer:
Name: google.com
Addresses: 2a00:1450:4014:80c::200e
172.217.23.206
JH Software
2 Mar 2019 13:24 UTC
JH Software
It could be that something like a firewall is blocking Simple DNS Plus from resolving the domain name.
What happens in the Simple DNS Plus log when you try this?
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23 Sep 2019 23:22 UTC
gareth
hi can u assist me please am tryna send an email using cmd but at nslookup it says default saver:unknown
adresss 127.0.0.1
then after set type=mx it says
***unknown cant find freeletter or if i had used gmail :no reapond from server
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