Conditional forwarders are not working

Question

_{Friday, July 13, 2018 3:08 PM}

Hi,

I have a very strange issue.

We have two domains and in one of them I made conditional forwarders for another.

I can ping these servers by IP, but they are shown as "not resolved" in DNS.

I can't ping this servers by their name - I get "Ping request could not find host XXXX . Please check the name and try again."

Then I ping domain name I get a response from external DNS server with public IP.

I can make nslookup by IP and get a response with all records for the remote domain.

I made /flushdns, of course.

I have no ideas what to check else.

Thanks for help

1

All replies (10)

_{Monday, July 16, 2018 6:14 AM}

Hi,

Thanks for your question.

Is the version of your server Windows 2008? If yes, there is a hotfix available.

Please refer to the link below:

https://support.microsoft.com/en-us/help/2625735/dns-queries-for-external-domains-are-not-resolved-when-you-use-conditi

If not, try reconfiguring the DNS conditional forwarder.

Please refer to the link below:

/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/cc754941%28v%3dws.10%29

Best regards,

Travis

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_{Monday, July 16, 2018 7:34 AM}

Hi,

I'm not sure about 2008, I hope not. I'm using Azure AD DS, so I can't connect to them directly by RDP.

I made reconfiguration 3 times, every time same issue.

Thanks

1

_{Monday, July 16, 2018 9:48 AM}

Hi,

Thanks for your reply.

Is there a reverse lookup zone established? If yes, create  PTR records of servers in the reverse lookup zone.

Please refer to the link below:

https://technet.microsoft.com/en-us/library/cc526435.aspx?f=255&MSPPError=-2147217396

Best regards,

Travis

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_{Monday, July 16, 2018 2:55 PM}

No reverse lookup zone was configured.

I configured option "allow zone transfer" from remote DNS servers, but without success with stub or secondary zone.

But in the same time I can use nslookup to query remote DNS servers by IP.

1

_{Tuesday, July 17, 2018 7:38 AM}

Hi,

Thanks for your reply.

As a work around, you need to configure a reverse lookup zone on DNS server. Your issue may be caused by the lack of PTR records.

Please refer to the link below:

https://technet.microsoft.com/en-us/library/cc526435.aspx?f=255&MSPPError=-2147217396 

Best regards,

Travis

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_{Tuesday, July 17, 2018 8:50 AM}

Hi, 

I tried to create reverse zone but no success with it(I can't load it from remote server, same as with stub, primary or secondary).

Situation is strange, because if my VM is using remote DNS server it works, but my DNS server can't use forwarders.

Thanks

1

_{Tuesday, July 17, 2018 11:38 AM}

After some research I found that if we using DNS server with conditional forwarders for remote domain (installed at management station) we can use it as one of DNS servers in our domain.

Name resolution is working at this case. So I assume that problem can be in Network Security Group in Azure or firewall issue at Azure AD DS servers (which I can't control).

Am I right that conditional forwarders are using same tcp 53 port as DNS servers? I already opened all traffic in Azure between networks,so it looks like Firewall issue.

Any ideas?

Thanks

1

_{Tuesday, July 24, 2018 3:16 AM}

Hi,

Was your issue resolved?

If you resolved it using our solution, please "mark it as answer" to help other community members find the helpful reply quickly.

If you resolve it using your own solution, please share your experience and solution here. It will be very beneficial for other community members who have similar questions.

If no, please reply and tell us the current situation in order to provide further help.

Best Regards,

Travis

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_{Monday, July 30, 2018 2:04 PM}

Hi,

problem was resolved.

We added a route to Azure and it's working now. But it is strange for me, because ping was working without this route.

1

_{Tuesday, July 31, 2018 7:32 AM}

Hi,

Thanks for your reply!
Good to hear that you have solved this issue by yourself. In addition, thanks for sharing your solution in the forum as it would be helpful to anyone who encounters similar issues.

Best regards,

Travis

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