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DNS resolving magically... RRS feed

  • Question

  • I'm not sure if this is the right forum spot for this, but thought someone else should see this.... I have two NICs setup on a "bridge" pc to bridge two domains together, a Dev domain and a Prod domain.  Both nics have a single DNS server pointing to 8.8.8.8 for googles DNS (no internal DNS),  BUT some how, a ping command to an internal server, resolves to a Dev or a Prod IP automagically... Any idea how these are resolving without local DNS servers configured on the NICs?
    Monday, April 13, 2015 8:20 PM

Answers

  • The name resolution may not be happening through DNS at all.

    By default if DNS name resolution fails then the machine will fall back to NetBIOS name resolution through broadcast. However the NetBIOS name resolution will only work for hostname and not FQDN.

    So if you try to ping 'ServerName' it will work but if you try 'ServerName.DomainName' it will not.

    Please test and let me know if this is happening in your environment

    You can also disable the NetBIOS by going to the nic card properties > select tcp/ip v4 > properties > advandced > wins tab.

    Another possibility is Link-Local Multicast Name Resolution (LLMNR) which was introduced since server 2008 for resolving name in a local network. However this also works only for single label names and not FQDN.

    You may refer to this article for more information https://technet.microsoft.com/en-us/library/bb878128.aspx

    • Marked as answer by JoeFri Thursday, October 24, 2019 1:27 PM
    Saturday, September 19, 2015 10:32 AM

All replies

  • Hi,

    prod and dev are active directory domains?


    Best Regards,

    Jesper Vindum, Denmark

    Systems Administrator

    Help the forum: Monitor(alert) your threads and vote helpful replies or mark them as answer, if it helps solving your problem.

    Wednesday, April 15, 2015 11:28 AM
  • correct, but they are basically duplicates of eachother, and therefore don't have access to eachother.  But  have a "bridge" terminal server built, that's not a member of either domain, that has two nics, and the ability to connect to both domains.  both nics using googles dns (8.8.8.8)  yet somehow, internal DNS addresses are still resolving...
    Wednesday, April 15, 2015 12:51 PM
  • Any idea's here?

    bump

    Monday, May 4, 2015 7:52 PM
  • How are the dns setup on the domain controllers for each domain?

    _


    Best Regards,

    Jesper Vindum, Denmark

    Systems Administrator

    Help the forum: Monitor(alert) your threads and vote helpful replies or mark them as answer, if it helps solving your problem.

    Monday, May 25, 2015 11:04 AM
  • It's AD DNS, not sure what you mean by how.  The piece I'm confused is how a static DNS config on a nic to use google 8.8.8.8 is resolving our internal names.
    Tuesday, August 18, 2015 12:30 PM
  • The name resolution may not be happening through DNS at all.

    By default if DNS name resolution fails then the machine will fall back to NetBIOS name resolution through broadcast. However the NetBIOS name resolution will only work for hostname and not FQDN.

    So if you try to ping 'ServerName' it will work but if you try 'ServerName.DomainName' it will not.

    Please test and let me know if this is happening in your environment

    You can also disable the NetBIOS by going to the nic card properties > select tcp/ip v4 > properties > advandced > wins tab.

    Another possibility is Link-Local Multicast Name Resolution (LLMNR) which was introduced since server 2008 for resolving name in a local network. However this also works only for single label names and not FQDN.

    You may refer to this article for more information https://technet.microsoft.com/en-us/library/bb878128.aspx

    • Marked as answer by JoeFri Thursday, October 24, 2019 1:27 PM
    Saturday, September 19, 2015 10:32 AM
  • Hey Sam,

    Sorry for the 3 year delay here... lol but even with NetBios disabled, the DNS name still resolves to an internal IP. This LLMNR appears to potentially be the culprit.  If I ping "DC01" it resolves if I ping "DC01.domain.local" it fails. 

    Thursday, October 24, 2019 1:27 PM