This document describes how to configure NTP servers on your virtual machines (VMs) to behave properly in the case of a leap second. Google NTP servers and leap... · Configure NTP for your instances
You can customize the Network Time Protocol server, as follows: Select Use GCP's NTP Server to enable cluster nodes to connect to the GCP internal time servers.
All Google Cloud Applications and APIs use the same NTP server time source including Cloud Functions, Cloud SQL, Datastore, BigTable, BigQuery, and DataFlow.