What Server are we syncing Time with?

We have a ruby docker image running on Aptible. What time server is the instance syncing with? time.nist.gov? Amazon TimeSync?

Hello! All Aptible Deploy containers inherit clock configuration from the underlying instances, all of which are synced to the default Ubuntu time servers using ntpd:

0.ubuntu.pool.ntp.org
1.ubuntu.pool.ntp.org
2.ubuntu.pool.ntp.org
3.ubuntu.pool.ntp.org

Great thank you!