It has passed somewhat unnoticed but Google have made available to us their free, accessible to all NTP servers. I have been using their DNS servers for years without any issues so will trust their NTP ones as well. So far works just fine. For a single server we can use time.google.com and for multiple servers, even though they all seem to be in the same class C yet I get different latencies - from 85 msec up to 185 msec, we can use time1.google.com, time2.google.com, time3.google.com, time4.google.com .