none
DNS - Conditional Forwader stops working after 30 sec. RRS feed

  • Question

  • Hi All,

    My company is facing a very weird problem.

    We have a location that is connected to another company (Site to Site Tunnel) and we want to ask their DNS Servers to resolve certain URLs in their network. Therefore we enabled a conditional Forwarder on the Domain Controller in the location that is asking two DNS Servers at the other companys network.

    We are able to resolve the DNS Name with the IP address an once we enabled the conditional Forwarder its working for 20 to 30 sec. but then stops forwarding requests.

    After we epmty the DNS Cache its working again and stops working after another 30 sec.

    Please let me know if you had this issue before.

    best regards,

    Adrian

    Monday, July 18, 2016 2:33 PM

Answers

  • Hi,

    Although this KB is for 2012r2,you could also check you DNS server's cache.Please try to manually set DNS server cache TTL to 0,and test again.

    PS C:\> Set-DnsServerCache -MaxTtl 0

    REF:Set-DnsServerCache

    https://technet.microsoft.com/en-us/library/jj649852(v=wps.630).aspx

    ________________________________________
    Best Regards,
    Cartman
    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.

    Friday, July 22, 2016 2:46 AM

All replies

  • Hi,

    >>After we epmty the DNS Cache its working again and stops working after another 30 sec.

    According your description,it seems the NS records from the delegations are cached by using a conditional forwarder. However, the DNS server does not forward the DNS queries for external domains if the cached NS records have not expired.

    You should check this KB:

    DNS queries for external domains are not resolved when you use Conditional Forwarding in Windows Server 2008

    https://support.microsoft.com/en-us/kb/2625735

    ________________________________________
    Best Regards,
    Cartman
    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.

    Tuesday, July 19, 2016 7:12 AM
  • Hi Cartman,

    Thanks for your answer but since we are using Windows Server2012R2 your suggested KB wont work for us. 

    We can resolve the names for 30 sec. without any problems - but then all over sudden the names cant be resolved until we delete the DNS Cache...

    best regards,

    Adrian

    Wednesday, July 20, 2016 8:45 AM
  • Hi,

    Although this KB is for 2012r2,you could also check you DNS server's cache.Please try to manually set DNS server cache TTL to 0,and test again.

    PS C:\> Set-DnsServerCache -MaxTtl 0

    REF:Set-DnsServerCache

    https://technet.microsoft.com/en-us/library/jj649852(v=wps.630).aspx

    ________________________________________
    Best Regards,
    Cartman
    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.

    Friday, July 22, 2016 2:46 AM