Exchange 2013 Round Robin failed

John Jiao 1 Reputation point
2021-11-22T08:54:27.08+00:00

I have two Exchange 2013 server, configured HUB and DAG on each server.

and used dns round robin in DNS server

When I restarted one of exchange server, after 5 mins all outlook reconnected.

But if I shutdown one of exhange server, all outlook disconnected exchange server, at the same time, I found the outlook dns record pointed live exchange server, but still disconnected.

Can someone help me?

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Andy David - MVP 110.1K Reputation points Microsoft MVP
    2021-11-22T13:45:03.903+00:00

    Yes, I would recommend using a true load balancer. DNS Round Robin, while supported, is not a good solution for these reasons.
    If you use DNS Round Robin, you may also have to restart clients etc. at times..In your case, restarting Outlook may fix this

    Note that others see this too:
    https://learn.microsoft.com/en-us/answers/questions/171904/dns-round-robin-for-exchnage-server-2016-cas.html

    https://learn.microsoft.com/en-us/exchange/load-balancing-exchange-2013-help

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  2. Joyce Shen - MSFT 16,331 Reputation points Microsoft Employee
    2021-11-23T06:41:15.507+00:00

    Hi @John Jiao

    Yes, this seems to be a normal behavior. DNS round-robin does not provide fault tolerance for high availability, it doesn't care about whether is the server is running, it just round between those IP pool. Clients will hit a down machine that's still in DNS and probably won't try a different one.

    We could refer to this link to know more about Exchange 2016 DNS Round Robin Load Balancing (Part 1)
    Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.


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