My standalone server is connected and taking time from a dedicated NTP hardware that is synced to UTC through GPS. All clients in the network are connected to this stand alone server and the clients are configured to take this server as their NTP time source (by going to gpedit.msc / computer configuration / admin. Templates / system / windows time service/time providers and configuring windows NTP client) after disabling network time protocol service and stopping windows time service until the above configuration is done and started again.
After completing the above configuration in all clients (about 25 nos; 4 of which are virtual servers; when i verify the time of each client with respect to the physical server that takes time from NTP hardware source, i find time difference ranging from 0 seconds to 5 seconds. While the differences in the order of less than one second (in milliseconds) does not bother me or my application, i need accuracy in the order of seconds between all clients and the server within the standalone network.
Please let me know if I need to give any more information / help me identify what am I missing that still allows this time difference between my clients to exist.