restrict default noquery nomodify

restrict 127.0.0.1

server ntp.nasa.gov
server time.apple.com
server 17.254.0.26
server 17.254.0.27
server 17.254.0.28
server 17.254.0.31
server 17.254.0.49
server 17.254.1.70

driftfile /var/ntp/ntp.drift
logfile /var/log/ntp.log
pidfile /var/run/ntpd.pid