Exchange 2016 is a DAG cluster consisting of two nodes in different subnets.

Cobion 111 Reputation points

Hello everyone We have a DAG cluster of two Exchange 2016 Std.5 Databases and 300 mailboxes in our office. Each node of the cluster has two NICs (MAPI and Replication) on the same network and a shared witness folder. As part of building a fault-tolerant infrastructure, one of the nodes of the Exchange cluster will be moved to the Data Center. The Data Center has a different subnet, but in the same Active Directory site. There is a 1gbit/s bandwidth channel between the central office and the data center. Please tell me, is there a standard scheme for dividing two nodes of the same DAG cluster in different subnets and how to do it correctly and recommended? On one of the nodes, the addresses will change to the MAPI NIC and replication. Is it possible to use NICs for replicas for different networks?

A little clarification. The Active Directory site is bound to the subnet mask 16. But we use addressing by 24 mask. If I change the mask from 24 to 16 on the Exchange nodes, will this mean that logically then the nodes are in the same subnet and additional settings will then be required. Or is it impossible to do this, since this may affect the anti-spam clients and border servers? Thanks!

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 120.5K Reputation points MVP

    You can simply Change the IP on that existing server and it should be fine - as long as the two subnet can communicate.

    "In this example, the MAPI network in each DAG member is on a separate subnet. As a result, the DAG requires two IP addresses, one for each subnet on the MAPI network. -"

    This is referring to the quorum CNO object I was referring to before. If your cluster isnt using an IP now, then you dont need to do this.

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  1. Andy David - MVP 120.5K Reputation points MVP

    Yes, you can absolutely do that. All you need is is an additional IP for the cluster node if you are using an IP based cluster. If you are using IP-less CNO, then no need to add the additional IP of course.
    The IP must be an IP on the other subnet. Depending on which server owns quorum, only one of those cluster IPs will be pingable at any one time

    BTW, there really is no need for a replication network. You can remove it

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  2. Cobion 111 Reputation points

    That is, all you need is to turn off the balancing, move the virtual machine to another subnet and change the IP address (indicated in the screenshot), specify a new IP address in DNS, and you can delete the subnet for replication (as shown in the screenshot)?



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  3. Andy David - MVP 120.5K Reputation points MVP

    Well, you can have a REPL network, just not recommended anymore in most cases.

    Does the cluster have an existing IP address?

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  4. Cobion 111 Reputation points

    No, just the cluster name.

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