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Windows Server 2008 R2 Thread, NIC DNS Settings in Technical; Hi everyone, I know this is my first post... Just a quick question for those who are sharp with DNS. ...
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    NIC DNS Settings

    Hi everyone, I know this is my first post...




    Just a quick question for those who are sharp with DNS.


    Our school has 2 domain controllers, both have the DNS role installed and is running fine. On the NIC DNS settings for both DC's, the primary DNS is set for the 1st DC and the secondary DNS is set for the 2nd DC. It's been set like this for a number of years and I've had no problems however yesterday my colleague decided to change the secondary DNS on all the servers to an external DNS server.


    Is this the right thing to do? As far as I'm aware you would set the domain controllers to look at each other for DNS queries. Since the change there has been issues with people logging on etc. but I don't want to jump to conclusions here!




    Any insight is very much appreciated!

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    Absolutely not, what your colleague has done will have a negative impact on your system.

    DNS Servers have a special section within their configuration called "Forwarders" which is where your ISP / External DNS servers can go, so they are only used if your DNS servers don't know the answer.

    Steer your colleague to the DNS best practices analyser - DNS: DNS servers on <adapter name> should include the loopback address, but not as the first entry

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    TheMotherload (2nd July 2014)

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    Thanks for that, so from what I gather it should be;

    1st DC

    Preferred DNS : IP of 1st DC
    Alternative DNS : IP of 2nd DC

    2nd DC

    Preferred DNS : IP of 1st DC
    Alternative DNS : IP of 2nd DC

    Or is the direct IP considered as the loopback and it needs to be the opposites?


    Cheers!

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    What you have there is correct. Some people use 127.0.0.1 but i wouldnt recommend that

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    TheMotherload (2nd July 2014)

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    Thank you.

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    Quote Originally Posted by glennda View Post
    What you have there is correct. Some people use 127.0.0.1 but i wouldnt recommend that
    Just curious. Why wouldn't you recommend using localhost?

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    Quote Originally Posted by Sam_Brown View Post
    Just curious. Why wouldn't you recommend using localhost?
    Not 100% sure i read it somewhere years ago in a M$ article, I think it is just best practice not too but it is quite a topic of conversation with various people thinking different things (even Microsoft Engineers!)

    2K8 - Best practice for setting the DNS server list on a DC/DNS server for an interface

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    Quote Originally Posted by Sam_Brown View Post
    Just curious. Why wouldn't you recommend using localhost?
    Have a look at the best practices analyzer link I posted above, it explains why if you set it as a primary bad things /could/ happen.

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    Me again, We have experienced some problems with my network after my original posts... here is what I've done;

    I have reverted the changed DNS settings on all of the servers back to the originals but I still seem to be getting some problems... I have cleared the DNS Server cache and set GPO to clear cache on all of the client computers but the issues still persist. If I do an ipconfig /all on my computer it will still display the external DNS server. this is after a manual flushdns and renew of the ip address.

    I'm not sure how to troubleshoot from here any suggestions?

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    Quote Originally Posted by TheMotherload View Post
    Me again, We have experienced some problems with my network after my original posts... here is what I've done;

    I have reverted the changed DNS settings on all of the servers back to the originals but I still seem to be getting some problems... I have cleared the DNS Server cache and set GPO to clear cache on all of the client computers but the issues still persist. If I do an ipconfig /all on my computer it will still display the external DNS server. this is after a manual flushdns and renew of the ip address.

    I'm not sure how to troubleshoot from here any suggestions?
    On your local machine or on the domain controller itself?

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    Quote Originally Posted by glennda View Post
    On your local machine or on the domain controller itself?
    Local PCs, the DCs reflect the DNS servers fine.

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    Quote Originally Posted by TheMotherload View Post
    Me again, We have experienced some problems with my network after my original posts... here is what I've done;

    I have reverted the changed DNS settings on all of the servers back to the originals but I still seem to be getting some problems... I have cleared the DNS Server cache and set GPO to clear cache on all of the client computers but the issues still persist. If I do an ipconfig /all on my computer it will still display the external DNS server. this is after a manual flushdns and renew of the ip address.

    I'm not sure how to troubleshoot from here any suggestions?
    Someone did something like that here a while ago... It took best part of a week to iron out all the DNS issues as machines didn't flush for ages. We enede up doing manual flush and check whenever an issue cropped up.

    Hold the phone... Has he set the DNS servers in DHCP options too?
    Last edited by Oaktech; 14th July 2014 at 02:08 PM.

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    Quote Originally Posted by Oaktech View Post
    Someone did something like that here a while ago... It took best part of a week to iron out all the DNS issues as machines didn't flush for ages. We enede up doing manual flush and check whenever an issue cropped up.
    That's what I've been doing, it was bad last week and not so bad now but I don't why my client PC, for example is still showing the old external DNS in its list.
    Last edited by TheMotherload; 14th July 2014 at 02:33 PM.

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    Quote Originally Posted by TheMotherload View Post
    That's what I've been doing it was bad last week and no so bad now but I don't why my client PC for example is still showing the old external dns in its list.

    I think it's in DHCP scope options...Clipboard01.jpg

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    TheMotherload (14th July 2014)

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    That pic doesn't load for me

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