Simple Network Time Protocol (SNTP) is a simplified, client-only version of NTP. SNTP can receive only the time from NTP
servers; it cannot be used to provide time services to other systems.
SNTP typically provides time within 100 milliseconds of the accurate time, but it does not provide the complex filtering
and statistical mechanisms of NTP. In addition, SNTP does not authenticate traffic, although you can configure extended access
lists to provide some protection. An SNTP client is more vulnerable to servers that have unexpected behavior than an NTP client,
and should be used only in situations where strong authentication is not required.
You can configure SNTP to request and accept packets from configured servers or to accept NTP broadcast packets from any
source. When multiple sources are sending NTP packets, the server with the best stratum is selected. (See the
Network Time Protocol section on page 3 for a description of strata.) If multiple servers are at the same stratum, a configured server is preferred
over a broadcast server. If multiple servers pass both tests, the first one to send a time packet is selected. SNTP will choose
a new server only if it stops receiving packets from the currently selected server, or if a better server (according to the
criteria described) is discovered.