Good Public NTP server for Callmanager and Unity?

[hankej]

I have been having many, many issues with my callmanager and Unity servers becoming unsynchronized with the NTP server.  I have a TAC case open and they said "

If this is also happening for CUCM cluster, I suggest changing the NTP server. Cisco recommends using a Linux based NTP server since it is more stable. A NTP server unsync could bring serious issues like a replication problem which can extremely affect the production."

I currently am pointing my CUCM and Unity Publisher servers to Google.  I'm not sure if they are Linux based or not.  Is there a good, Linux based NTP server that you use?  I am in North America.

Thanks

[Vaijanath Sonvane · Accepted solution]

Hi,

I used NIST NTP public servers. These are reliable and has stratum 1 or 2. Choose the one closer to your area.

https://tf.nist.gov/tf-cgi/servers.cgi

[Nithin Eluvathingal]

I always sync my core switch  with time.google.com and use core as ntp for CUCM and unity. No where I faced issues.