Setting up DAG for site-failover in Exchange Server 2016

Usama A. Rub 146 Reputation points
2022-05-17T16:01:28.097+00:00

I have to deploy a basic DAG for my Exchange Server 2016. I have prepared 2 mailbox servers (1 in primary site and 1 in colocation site) on Windows Server 2016 and 1 witness server.

Now i want that if my primary site goes down, my exchange server doesn't stop working.

My questions are:

  • For this purpose do i have to configure same internal urls in virtual directories for both sites? (We don't need external access so external url not required)
  • Do i have to setup 2 separate network cards for replication and MAPI with different subnets (as mentioned in some documents) and if yes, then why?
  • Any manual setting required in DNS ?
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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Accepted answer
  1. Andy David - MVP 139.8K Reputation points MVP
    2022-05-17T17:57:50.707+00:00

    With 2 servers and the file share witness in one of those data centers, you will have an outage if the primary goes down.
    The only way to achieve high availibility is to have a 3rd data center with the File Share Witness located there.

    Otherwise, you will be doing a data center switchover
    Here is the doc for that:

    https://learn.microsoft.com/en-us/exchange/high-availability/manage-ha/datacenter-switchovers?view=exchserver-2019

    Its preferred to use the same internal URLs, yes.
    You dont need to separate networks for MAPI and REPL. One is preferred:

    https://techcommunity.microsoft.com/t5/exchange-team-blog/the-exchange-2016-preferred-architecture/ba-p/604024

    If you are not using a load balancer, then you would need to remove the primary from the round robin DNS that points to the client access endpoints in the event the primary is down

    I recommend at least 3 servers, not 2. Two in the primary, one in the backup data center

    1 person found this answer helpful.

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  1. Andy David - MVP 139.8K Reputation points MVP
    2022-05-17T19:02:34.347+00:00

    If you only have one primary server, your org will be down if you ever need to perform any routine maintenance or upgrade on that server.

    If you are using a true load balancer, then when a server is down, you wont have to manually make any changes. If you are using DNS , then you will have to remove the primary server from DNS so clients wont use it.

    1 person found this answer helpful.
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