Violation of pool.ntp.org Terms of Services

[phlipse]

The default update time of 60 seconds violates the terms of service of the pool.ntp.org project.
Especially the following section:
4. End-User agrees that he or she will not:
(b) Request time from the Services more than once every thirty (30) minutes (ideally at even longer intervals), if using SNTP.
For reference: https://www.pool.ntp.org/tos.html

Everybody participating from such a free service should at least respect the terms of service when using it.
Please adjust your default update time to something like 24 hours or even more.
Many users will blindly use the default value without the need of updating it once a day at all. If they have a real need they should set it on their own to something more applicable.

[taligentx]

I was surprised by this as well - the native SNTP client on Arduino/esp8266 and Arduino/esp32 syncs once per hour, regardless of how often the time is checked.

[mlichvar]

It seems there are some arduino NTP clients (using the 1N14 reference ID) configured with extremely short intervals, causing public servers in pool.ntp.org to receive from some IP addresses 50-90 NTP requests per second. It's reported here: https://community.ntppool.org/t/high-request-rates-from-nixie-clocks/3338

Please consider forcing a minimum value of updateInterval, e.g. 1000 milliseconds.

[hart-NTP]

FYI, ntpd with rate-limiting ([code]restrict default ... limited[/code]) rejects queries that are less than 2 seconds apart in bursts of 8 or less, or that average less than 8 seconds apart. If kiss-of-death is enabled, some rejected queries get a useless response intended to request the client back off its polling interval to the value provided in that response.

I would argue for a default minimum of 8000 ms.