Addressing vCenter FQDN and Hostname Case Mismatches

Products

• VMware vCenter Server 7.0
• VMware vCenter Server 8.0

Issue/Introduction

If the destination PNID is too similar to the original PNID, the update may fail. This typically occurs when transitioning from a short hostname to an FQDN or from an uppercase FQDN to a lowercase FQDN.

This procedure is designed to handle such cases effectively. For example, consider the plan to change the PNID as follows:

• Original PNID: VCSA01.domain
• Destination PNID: vcsa01.domain.local
• DNS record: examplevCenter.example.local -> ###.###.###.###

Attempting to directly change the PNID from VCSA01.domain to vcsa01.domain.local often results in errors. To avoid this, the task should be completed in two steps:

1. Change the original PNID to a temporary PNID.
2. Then, change the temporary PNID to the final PNID.

For example:
example.domain -> exampletemp.example.com -> example.example.com

The proxy DNS service (dnsmasq) in the vCenter Appliance is used to resolve the temporary PNID exampleTemp.example.com. This eliminates the need to update external DNS servers with the temporary PNID.

Note: Starting from VCSA 6.7 U3 or later versions, the PNID can be updated through the VAMI interface.

Environment

VMware vCenter Server 7.x

VMware vCenter Server 8.x

Resolution

Procedure:

Step 1: Create Snapshot and Backup vCenter Configuration

• Take a snapshot of the VCSA vm and back up the vCenter configuration.
• If the vCenter is a single standalone vCenter, you can take a online (powered-on) snapshot. If the vCenter Server is part of ELM, take offline (powered-ff) snapshot of all the vCenter Servers VMs which are part of the setup.
• These backups will be used for rollback if needed.

Step 2: Update the VCSA Hosts File

• Edit the VCSA's /etc/hosts file to retain only the content between # VAMI_EDIT markers:
   

  # VAMI_EDIT_BEGIN ... # VAMI_EDIT_END

Step 3: Configure Temporary PNID in VCSA Proxy DNS

1. Backup the original configuration:
    

   # cp /etc/dnsmasq.conf /etc/dnsmasq.conf.original

    
2. Edit dnsmasq.conf to include the hosts file:
    

   # vi /etc/dnsmasq.conf addn-hosts=/etc/dnsmasq.hosts

    
3. Add the temporary PNID to /etc/dnsmasq.hosts:
    

   # vi /etc/dnsmasq.hosts

    
   Add the following line:
    

   ###.###.###.### exampleTemp.example.com exampleTemp

    
4. Restart the dnsmasq service:
    

   # systemctl restart dnsmasq.service

    
5. Test name resolution:
    

   # nslookup exampleTemp.example.com 

   # nslookup ###.###.###.###

Step 4: Change PNID to Temporary PNID in VAMI

• Access the VAMI interface at https://VCSA:5480.
• Change the PNID to vcsa01temp.domain.local.
• Note: It is recommended to add vcsa01temp.domain.local to the local hosts file of the web browser's PC to ensure accessibility to the VAMI interface.

Step 5: Reboot and Verify

• If the PNID change is successful, reboot the VCSA.
• Verify that all vCenter services are running as expected.
• Important: If any errors occur, roll back to the snapshot.

Step 6: Remove Temporary PNID Configuration from Proxy DNS

1. Restore the original configuration:
    

   # cp /etc/dnsmasq.conf.original /etc/dnsmasq.conf

    
   or manually remove the line added earlier:
   
   addn-hosts=/etc/dnsmasq.hosts

    
2. Delete the temporary hosts file:
    

   # rm /etc/dnsmasq.hosts

    
3. Restart the dnsmasq service:
    

   # systemctl restart dnsmasq.service

    
4. Test name resolution:
    

   # nslookup example.example.com

   # nslookup ###.###.###.###

Step 7: Change PNID to Destination PNID in VAMI

• Access the VAMI interface at https://VCSA:5480 and change the PNID to the final destination PNID: example.example.com