NTP Fundamentals

Computers have to maintain a clocking mechanism to be able to maintain the time, although it's not very accurate. In a Sun system, the non-volatile RAM (NVRAM) chip keeps time when Solaris is not running, and when the system starts up, the time value is copied into a counter that the Solaris 9 kernel uses. For most Ultra-based systems, the counter is 64 bits in length. The clock is not very accurate because it relies on an oscillator generating regular interrupts that need to be processed by the CPU, so if the CPU is very busy, this could be delayed and cause drift (explained later).

The 32-bit counter present in older systems ...

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