When doing an ASR Failover (not a Test Failover, but actual Failover) I want to ensure same IP in DR Region for the VM

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When doing an ASR Failover (not a Test Failover, but actual Failover) I want to ensure same IP in DR Region for the VM

Rob McNees 361

How can I make sure that the same IP address on a VM after failover gets assigned to the VM in the DR Region? First of all, we will bring down application and stop the VM in the primary region prior to doing the "Failover" - using this procedure: https://free.blessedness.top/en-us/azure/site-recovery/azure-to-azure-tutorial-failover-failback (we are not going to a failback (Or not replicate Dr testing data back from DR region to primary region) so no "Re-Protect", but will bring up primary servers only back in primary region). Since this is our first attempt of doing a "real" failover, we need the advice on how to make sure we can keep the same IP address.

Other notes:

The NIC on the primary servers are Dynamic per the attached screen shot: plm2023qasearchvm00-nic.jpg but I'm hoping that when VM, this NIC is attached to, gets shut down in primary region prior to Failover, that we can assign the same IP in the DR Region when it comes up there.
Please provide advisement on how we can achieve keeping the same IP in DR Region.
I have spoken with @vinod pittala and he has been very helpful on advisement on "failovers"

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Answer 1

Hello Rob McNees,

Here’s how you can achieve that:

Ensure Identical Networks: Before the failover, make sure that the network architecture in the DR region is identical to the source region. This means having the same address spaces and subnets in both the source and the DR regions. This setup allows the Azure Site Recovery (ASR) to map the IP addresses correctly.
Use Static IPs: If possible, switch your VM's NIC (Network Interface Card) configuration from Dynamic to Static IP. Azure Site Recovery typically tries to retain the original static IP address during failover if it's not in use.
Pre-assign IP Addresses: In the SQL Server Always On availability groups example, they assign or verify target IP addresses for the replicated items. Before initiating the failover, verify and assign the target IP addresses in the DR region to match those from the primary. Make sure that before you initiate failover, these assignments are correctly in place.
Perform the Failover: Once everything is set and you have verified the configurations, follow the failover process as detailed in the Azure documentation. Azure Site Recovery will attempt to allocate the IP addresses as per the configurations you set.

You referred to stopping the applications and shutting down the VM in your primary region, which is good practice. Just ensure that all your IP assignments are done before you start the failover process.

For more detailed guidance, you can check out the Azure documentation on retaining IP addresses during failover here.

Rob McNees 361 Reputation points

2025-10-17T19:57:54+00:00

Thanks Siva for the great direction. Do you think it would help if that even after we stop the primary servers (shut down app, then shut down VM), I should go into the "Network" blade under the "Replicated Items" and hard code IP - or put Static? It had DHCP, but that was only used when the NIC secured the IP (from the CIDR), the IP does not change in the primary server - see attached for reference.PLM-QA-Network-RepItems.jpg
Siva shunmugam Nadessin 1,990 Reputation points Microsoft External Staff Moderator

2025-10-20T04:26:06.08+00:00

Hello Rob McNees,

ASR replicates the NIC configuration, but during failover, the IP assignment depends on the target network settings. If the source VM uses DHCP, the failover VM will also default to DHCP unless overridden.

Why Static Helps: If your application or downstream systems rely on a fixed IP, setting a Static IP in the failover settings ensures consistency after failover. Otherwise, DHCP could assign a different IP, breaking dependencies.

Where to Configure:

In the Network blade → Replicated Items → Failover Settings, you can:

Switch from DHCP assigned to Static.

Enter the same IP as the source in your case, provided:

The IP is available in the target subnet.

No conflicts exist in the recovery region.

Thanks.

Answer 2

Jeff Pigott 395 Microsoft Employee

Hi Rob, it has been a minute since I wrote this blog on a similar topic keeping the same MAC Address. But could be something to review as it could also keep the same IP address if I recall.

https://jpigott.com/2023/11/azure-site-recovery-maintaining-a-persistent-mac-address/

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When doing an ASR Failover (not a Test Failover, but actual Failover) I want to ensure same IP in DR Region for the VM

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