I have 18 DCs, my PCD emulator is configured according to KB article https://support.microsoft.com/en-us/kb/816042, pointing to pool.ntp.br
C:\>nslookup pool.ntp.br
Server: srv-rjo-004.qgog.ad
Address: 10.21.32.9
Server: srv-rjo-004.qgog.ad
Address: 10.21.32.9
Non-authoritative answer:
Name: pool.ntp.br
Addresses: 2001:12ff:0:7::186
2001:12ff:0:7::193
2001:12ff::8
200.192.232.8
200.20.186.76
200.160.0.8
200.160.7.186
200.160.7.193
200.186.125.195
200.189.40.8
My 2 main DCs in central datacenter are perfeclty synchronized with external time servers, including PDC emulator
But...
Some DCs are getting time from a crazy and satellite-connected DC, i´m sure that nobody did that, checked by w32tm /source
A lot of users are 11~=~minutes late.