Unable to update the NTP server configuration on the vCenter Server Appliance due to time synchronization failures.

Products

• VMware vCenter Server

Issue/Introduction

Configure Network Time Protocol (NTP) settings on a vCenter Server Appliance (VCSA) to ensure accurate time synchronization across the vSphere environment. Accurate time is critical for certificate validation, logging, and database operations within VMware vCenter Server 7.x and 8.x.

• "Failed to retrieve time from the NTP server" error during upgrade or configuration.
• Running ntpdate -d <NTP_Server_IP> returns "Server dropped: no data".

Environment

• VMware vCenter Server 7.x
• VMware vCenter Server 8.x

Cause

Time synchronization failures typically occur due to one of the following:

• Bidirectional network communication is blocked on UDP Port 123.
• Stateful firewalls drop the return path traffic from the NTP server to the VCSA.
• The target NTP server is configured to ignore requests from the VCSA subnet.

Resolution

1. Verify bidirectional network connectivity for UDP Port 123 between the VCSA and the NTP server.
2. Open a web browser and navigate to https://<VCSA_FQDN_or_IP>:5480.
3. Log in as the root user.
4. Select Time in the navigation pane.
5. Click Edit in the Time zone and time synchronization section.
6. Select NTP from the Mode dropdown menu.
7. Enter the NTP server IP addresses or FQDNs, separated by commas.
8. Click Save.
9. To verify synchronization from the command line, run: ntpdate -d <NTP_Server_IP> Confirm that valid stratum and offset data payloads are returned.

Additional Information

• Add or Set an NTP Server in the vCenter Server Appliance
• For assistance, see Contact Broadcom Support.