After vCenter Server certificate updated, all ESXi hosts have become not responding.

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

Symptoms

• Attempting to reconnect to the ESXi host with the vSphere Client fails due to a network error.
• The ping commands from vCenter to each ESXi host's IP address succeed.
  
• The ping commands from vCenter to each ESXi host's FQDN fail .
• The  nslookup command fails for the IP address/FQDN of each ESXi host.

Environment

VMware vCenter Server 7.x
VMware vCenter Server 8.x
VMware vSphere ESXi 7.x
VMware vSphere ESXi 8.x

Cause

This issue occurs because vCenter Server cannot resolve the name of the ESXi host.
Even in cases where there were originally issues connecting to or receiving responses from the DNS server, problems may become apparent after updating the vCenter Server certificate or after a restart.
This is because DNS cache information is refreshed in vCenter Server when vCenter Server certificates are updated or when vCenter Server is restarted.
In this scenario, certificate renewal or restart operations in vCenter Server are not the cause of this issue.

Resolution

Investigate and resolve issues with the DNS server itself and its routing to enable name resolution for ESXi hosts.

Temporary Workaround : Until the DNS server issue is fixed, you can temporarily resolve the problem by adding the ESXi host information to the vCenter Server's /etc/hosts file.

Additional Information

• Troubleshooting an ESXi host in a "not responding"/"disconnected" state
• vCenter Server の証明書を更新した後、すべての ESXi ホストが応答なしになる