Vagrant boxes are getting out of sync, but prod boxes aren't, I think it's because vagrant boxes have different server than the prod boxes, add all these:
server ntp.ubuntu.com
server 0.north-america.pool.ntp.org
server 1.north-america.pool.ntp.org
server 2.north-america.pool.ntp.org
server 3.north-america.pool.ntp.org
server 0.pool.ntp.org
server 1.pool.ntp.org
server 2.pool.ntp.org
server pool.ntp.org
Vagrant boxes are getting out of sync, but prod boxes aren't, I think it's because vagrant boxes have different server than the prod boxes, add all these:
from feb 2016 PRIVATE_REPO_ISSUE#20