I was working with one of my customer. He wanted to change IP/Subnet/AD site for an existing DAG member.
Changing subnet for existing DAG member server.
Change of AD site and IP/Subnet range in your organization.
Exchange 2010 SP1 and later
Windows server 2008 R2 SP1
AD Site: 2+
Example Subnet change from 255.255.0.0/16 to 255.255.252.0/22
DAG networks and multiple subnet deployments:
In the preceding example, even though there are two different subnets in use by the DAG (192.168.1.0 and 10.0.0.0), the DAG is considered a single-subnet DAG because each member uses the same subnet to form the MAPI network. When DAG members use different subnets for the MAPI network, the DAG is referred to as a multi-subnet DAG. In a multi-subnet DAG, the proper subnets are automatically with each DAG network.
- We changed subnet in the network adapter on the target server.
- Checked under “Failover Cluster Manager” and it was updated.
- Checked DAG properties and found new subnet has been updated.
- Assigned new IP to the target server.
- Did ipconfig /flushdns to flush IP address.
- Did ipconfig /registerdns to register new IP.
- Still DAG is unable to pick new subnet.
- Requested the you to reboot the server.
- After reboot we can still see the server and network is down under “Failover Cluster Manager”.
- Also found DAG network is unable to bring the subnet online.
- Confirmed that you added new subnet to VLAN as well.
- As network is down under “Failover Cluster Manager” Microsoft involved cluster team.
- In the mean time you made changes in production and it was successful.
To accomplish this we need to perform below steps.
- Suspend mailbox databases copies on the target server.
- Stop mail replication on the node by using the suspend-mailboxdatabasecopy command
- Stop all Exchange Services on the target server.
- Stop the cluster service
- Change the subnet AND IP address on the network card/adaptor. Changing just the subnet itself will not write stuff correctly to the registry to make the change. This might be a Hyper-V issue.
- No need to delete the virtual NIC.
- Start the cluster service. Verify that the new cluster network was created with the correct subnet.
- REGEDIT and modify this key
- When we restarted the cluster service, Exchange populates this key with the OLD subnet of the server. Just need to change the part that was 10.2.0.0/16 with 22 on the end.
- Close registry editor
- Restart target server.
- Logon to the server and change the IP address back to original IP. Register with DNS
- Verify that the cluster service is still correct. It will show that the change node down
- Launch the EMC. Go to the DAG, remove the old subnet from the DAGNETWORK. Once you do this, it will create a new DAGNETWORK automatically with the correct subnet. Delete the DAGNETWORK (Old subnet network) that we changed since it’s not used anymore.
- Cluster service should show everything is happy. Wait until DNS replicates before starting replication.