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DNS settings check - NSLOOKUP - Default server unknown

Posted on 2011-10-03
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Last Modified: 2012-06-04
Hi,

I'm looking for some crash course assistance with setting up DNS. I want to make sure my Windows Server 2008 is configured correctly as I'm having issues with Group Policy.


Also when I do an NSLOOKIP I get:

Default Server: Unknown
Address: IP ADDRESS OF SERVER

Is this normal?

Then to make a server be able to server as a DNS for PC's on the network, what do you need as a minimum. I can see on this server that when I look up the Forwarders set for this domain Google DNS 8.8.8.8. has been entered.

Is this good practise?
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Question by:afflik1923
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Accepted Solution

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Adam Brown earned 2000 total points
ID: 36906959
Default Server: Unknown means that you don't have an entry for the server in the Reverse Lookup Zone, so it is normal if you haven't created a Reverse Lookup Zone in DNS. This won't affect the operation of your DNS server. AD doesn't really use Reverse DNS, so that won't hurt you.

Having a Forwarder to 8.8.8.8 on your DNS server configuration is fine, and a good way to handle DNS for the Internet. As long as you don't have 8.8.8.8 as a primary DNS server on your workstations and servers it won't be a problem.
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Author Comment

by:afflik1923
ID: 36907043
No, on the workstations we only have the server IP address as the DNS. So thi is all good then. I've actually fixed the group policy problem which prompted this question making me check, but not the MSSQL going very slow problem whcih was suggested might be the DNS setup.

Mayb it needs a reverse lookup?

Anyway thanks and any more pointers welcome (I know I've prvided limited info but you have already been helpful)
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LVL 44

Assisted Solution

by:Adam Brown
Adam Brown earned 2000 total points
ID: 36907072
There are a number of things that can make SQL operate slowly, but SQL doesn't really utilize reverse DNS either. RDNS is useful, but not a necessary element. It just makes it a lot easier to determine which Hosts have a specific IP address when all you have is the IP address.
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Author Comment

by:afflik1923
ID: 36907081
OK thanks. Will continue the investigation.
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Author Comment

by:afflik1923
ID: 36917004
Further problems. Users reported internet really slow, unabel to play internet radio and page not found.
I changed one workstatiaon direclty to have google 8888 as DNS and suddenly sorted.

On teh server I looked under the DNS manager

And looked under forward looup Zones and theright clicked on the site and then properties and I Can see that there is a single forwarder there but it says
<Unable to resolve>

Now again this is probably because I do not have reverse DNS setup but I want to be sure. Anything to help me resovle these issues

 DNS Forwarders
Any input welcome
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LVL 44

Assisted Solution

by:Adam Brown
Adam Brown earned 2000 total points
ID: 36917469
Might be some connectivity issues between you and that particular DNS server. If your ISP has a set of DNS servers, it's probably best to configure those ahead of Google's public DNS server.
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LVL 44

Assisted Solution

by:Adam Brown
Adam Brown earned 2000 total points
ID: 36917476
As a note, lack of a Reverse Lookup Zone on your internal network won't affect speed getting to sites outside your network. It shouldn't affect speeds inside your network either.
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Author Comment

by:afflik1923
ID: 36919170
OK I have switched over to the proper servers for the ISP. However I still think we have issues.

what can I look at on DNS server settings to make sure things are solid.

Other then adding forwarders so external DNS can be looked up. What else can be done to make sure the DNS settings are solid?

Any help much apprecaited.
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Author Comment

by:afflik1923
ID: 36919189
And also what should I do while there are problems. Things seem to be OK if I set a workstation DNS to have 8888 somewhere. That workstations performence seems to improve.
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LVL 44

Assisted Solution

by:Adam Brown
Adam Brown earned 2000 total points
ID: 36919246
Setting your workstations to 8.8.8.8 manually will actually cause some problems with Active Directory. Check your DHCP scope options and see what the DNS server settings are. If they are not set to point to the primary DNS server of your Internal network, it should be.
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Author Comment

by:afflik1923
ID: 36919462
NOTE: There is no DHCP on this network. Everything is static. Therefore workstaitons and server are all static addresses
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Author Comment

by:afflik1923
ID: 36919479
I should add the reason for the static network is that because for reasons beyond my control, the phscial network is shared with another network which does have DHCP from a router, but this is on a different subnet.

No time to go into why, but the point is before we put in the new servers, the old servers never had any issues like we have.
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Author Comment

by:afflik1923
ID: 36919488
As I'm keen to get as much info on this as possible, I have set up another thread whcih is more general specific DNS question, but I'm really greatful for all input.
http://www.experts-exchange.com/Networking/Protocols/DNS/Q_27382039.html
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Author Closing Comment

by:afflik1923
ID: 38046738
Belated response but thank you for this,
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