Why users connect to second DNS

Tutek 716 Reputation points
2023-03-10T13:29:00.2233333+00:00

Hi

I have just connected a second domain controller, in dhcp options clients have priority set dns1 - current server, dns2 - new server. I don't know why, but some clients use name resolution through DC2? The first DC1 works all the time.

Active Directory
Active Directory
A set of directory-based technologies included in Windows Server.
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  1. Dave Patrick 426K Reputation points MVP
    2023-03-10T13:55:22.5266667+00:00

    Something here could help.

    https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/dd197552(v=ws.10)?redirectedfrom=MSDN

    -

    --please don't forget to upvote and Accept as answer if the reply is helpful--

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  2. cthivierge 4,051 Reputation points
    2023-03-10T14:02:57.46+00:00

    This could be caused if the first DNS server is not able to response within 1 sec, then the client send the query to the second DNS server. After 15 minutes, the client reset the DNS priority list to the default settings...

    This article explain the process

    https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/dn593685(v=ws.11)#dns-client-resolver-behavior

    hth

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  3. Tutek 716 Reputation points
    2023-03-10T14:16:12.2433333+00:00

    I may have misspoken, users not only query the DC2 server but also log into it. There are logon events in event viewer. Why in this case they do not log on to DC1


  4. cthivierge 4,051 Reputation points
    2023-03-10T15:13:30.57+00:00

    Client computers will query the closest DC using DC Locator. If there is multiple DC's i the same site and all DC's have the same wright / priority, the clients may query any of them, the first DC to respond win.

    If you really want that all clients authenticate on a specific DC, you could change the priority and the weight of the DNS records but personally, i would not change those values except in really specific cases...

    https://learn.microsoft.com/en-us/answers/questions/1096119/client-authentication-to-active-directory

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