Effectively nmap on DC IP does not show an NTP service available:
# nmap -sU -p 123 192.168.122.77
Starting Nmap 7.40 ( https://nmap.org ) at 2017-01-11 12:32 CET
Nmap scan report for 192.168.122.77
Host is up (0.00016s latency).
PORT STATE SERVICE
123/udp closed ntp
If clients expect an NTP server running on a DC, we should add it!