The NTP configuration cannot be modified from an IP address to a FQDN

Products

• VMware vSphere ESXi

Issue/Introduction

• The NTP configuration cannot be modified from an IP address to a FQDN
  
  Operation failed!
Cannot change the host configuration.


• When performing an nslookup for the NTP FQDN via the ESXi command line, the following error is reported
  
  nslookup: read: Connection refused.
  
  
• Check the DNS configuration via command line, it was found that no DNS server has been configured. As a result, FQDN resolution is not possible.
  
  # esxcli network ip dns server list
DNSServers:

Environment

VMware vSphere ESXi 7.0.x
VMware vSphere ESXi 8.0.x

Cause

No DNS server has been configured. As a result, FQDN resolution is not possible.

Resolution

Add a DNS server configuration refer KB
How to change ESXi host name, FQDN and DNS server IP

# esxcli network ip dns server add -s <dns-server-ip-address>