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Marcus-9726 avatar image
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Marcus-9726 asked ·

How domain joined pc look for random domain controller if domain controllers in one site totally down

Just trying to understand more on this, assume that we have two AD site, site A and site B. Each site has two domain controllers with DNS. For client machine in each site the DNS server entries are configured for the site domain controllers. For example:

Site A is having domain controller 1 and 2. Site B is having domain controller 3 and 4. User machine is site A is configured with DNS server entries of domain controller 1 and 2. Then for site B machine the DNS is configured for domain controller 3 and 4.

In this case, if site A both domain controllers were down and the user machine in site A can still ping to site B domain controller. How the user machine look for domain controllers in site B automatically since both the DNS server entries were down? Will the machine cache the list of domain controllers in the first place during the DNS record lookup?

windows-serverwindows-active-directorywindows-dhcp-dns
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DSPatrick avatar image
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DSPatrick answered ·

Yes, it still can work.
https://social.technet.microsoft.com/wiki/contents/articles/24457.how-domain-controllers-are-located-in-windows.aspx

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


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DSPatrick avatar image
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DSPatrick answered ·

You can read here about the domain controller location process.
https://techcommunity.microsoft.com/t5/ask-the-directory-services-team/domain-locator-across-a-forest-trust/ba-p/395689

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Hi there,

105399-screenshot-20210614-205431.jpg



As per above image and also my question, if the DNS in site A is totally down, can the user machine complete the DC locator process even though there is no working DNS server anymore in site A?

Thanks

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VickyWang-MFST avatar image
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VickyWang-MFST answered ·

Hi,
I am glad to hear that your issue was successfully resolved. If there is anything else we can do for you, please feel free to post in the forum.
Best Regards,
Vicky

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