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# 1.2.1.20 SNTP Module

The SNTP module implements the Simple Network Time Protocol. The module updates its internal time periodically using a pool of public global time servers. It then calculates reference times on any call to TCPIP_SNTP_TimeGet using the system timer module.

The SNTP module is good for providing absolute time stamps. However, it should not be relied upon for measuring time differences (especially small differences). The pool of public time servers is implemented using round-robin DNS, so each update will come from a different server. Differing network delays and the fact that these servers are not verified implies that this time could be non-linear. While it is deemed reliable, it is not guaranteed to be accurate.

The system timer module provides much better accuracy (since it is driven by a hardware clock) and resolution, and should be used for measuring timeouts and other internal requirements.

The preferred time server can be changed. The default is to use the global pool.