The clock stratum determines the accuracy, which ranges from 1 to 16. The stratum of a reference
clock ranges from 1 to 15. The clock accuracy decreases as the stratum number increases. A
stratum 16 clock is in the unsynchronized state and cannot serve as a reference clock.
The local clock of an 3Com Switch 4500G cannot operate as a reference clock. It can serve as a
NTP server only after synchronized.