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When you must do business migrations or when one business buys another and there are different naming conventions, you need to change the vCenter Server DNS name. There might be other reasons why changing a FQDN on VCSA shouldn't be problematic in today’s virtualized infrastructures.
That is, until the VMware vSphere 6.7 Update 3 came out with this feature included. It is clearly a time saver and is very handy indeed, saving considerable work and time for any IT administrator.
While it might be easy to change the underlying IP and DNS information for Linux or Windows VMs, the whole vCenter server application and its dependencies must be taken care of. Many services rely on the DNS name, so that’s probably why VMware took its time before finally implementing this feature.
Before we go into the how-to configuration, you should know that there are some requirements that must be respected and tasks needing execution before and after your VCSA changes its DNS network name.
You should backup All vCenter servers that are in the SSO domain before starting any changes. You can use either the built-in file-level backup, allowing you to save the configuration, or use your usual backup software to back up all VCSA(s).
- If you're using backup, monitoring, or any other third-party software with vCenter server, unregister all those applications first, do the FQDN change, and then re-register them back with your vCenter.
- Make sure that the new FQDN/Hostname is resolvable to the IP address (DNS A records). Make sure that the resolution works in both directions.
- If you have a vCenter HA architecture (VCSAHA), this will need to be destroyed first. Yes, VMware recommends deleting the VCSAHA configuration prior to an FQDN change.
After your network settings have been reconfigured and your vCenter Server Appliance is up and running, make sure that you:
- Redeploy and re-register all your vCenter plugins;
- Regenerate all custom certificates;
- Recreate the hybrid Link with the Cloud vCenter server; and
- Rejoin your Active Directory (AD).
Changing the FQDN of a VCSA—the steps: ^
First, connect to the VCSA via the VAMI interface with port 5480. Just to let you know, the VAMI stands for "VMware Appliance Management Interface".
Connect to the vCenter Server VAMI interface (https://<FQDN-of-VCSA>:5480), then go to Networking > and click Edit.
A new wizard will start asking you to select the network adapter first. Go ahead and click the Next button to continue.
On the next screen, you can change the hostname and a DNS setting, if necessary.
Just below that, you'll find the settings for the IP address. Click the drop-down next to the NIC 0 and make any necessary changes.
Note: In case you make an error, VMware system won't let you finish with the assistant until you enter correct information (IP or FQDN).
As you can see, VCSA also supports an IPv6 now.
On this screen, you just need to fill in your Single Sign-On (SSO) credentials.
After that, acknowledge that you have made a backup of your VCSA. Note that there will be some downtime during the process of reconfiguration due to all the dependencies, such as the internal PostgreSQL database.
Note as well that the VCSA uses the embedded PostgreSQL database, which has scalability of up to 2,000 hosts and 35,000 virtual machines depending which option you chose during deployment.
After clicking the Finish button, you'll get a pop-up window showing the progress…
Once complete, you'll be automatically redirected to the correct FQDN address, so just log back into the VAMI user interface and check that everything is as expected.
Final words ^
This is a feature that many admins have asked for, but you must be sure to have backups of the VCSA (File-level or Image-level backups, both supported) just in case something goes wrong.
Make sure to validate all third-party software after you have made the FQDN change. You will need to reregister them with your vCenter server and, as mentioned earlier, you’ll have to rejoin Microsoft AD if that was your previous configuration.
With continuous changes to the platform, VMware keeps innovating and improving the VCSA product, as it is the central point of every vSphere datacenter-based environment.