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[on:]

More of a curiousity rather than a problem - my NTP implementation works fine...

But, every example of the Arduino NTP client code I've found online has a reference ID along the lines of:

  pb[12]  = 49;
  pb[13]  = 0x4E;
  pb[14]  = 49;
  pb[15]  = 52;

which ends up being "1N14". Does anyone know why this was chosen, rather than something that meets the NTP RFC, like "INIT", or perhaps the 4 octets of localIP(), with the stratum (byte 2, pb[1]) set to 16?

[Reply #1 on:]

which ends up being "1N14". Does anyone know why this was chosen,

1N14 is a model of Nixie Tube use in some Nixie Clock projects.

[Reply #2 on:]

in practice NTP doesn't care much what is in those 4 bytes AFAIK. You could try with different values and see what happens ...
(don't poll NTPservers more than once a minute, they don't like to be flooded.)

[Reply #3 on:]

1N14 is a model of Nixie Tube use in some Nixie Clock projects.

That's as good an answer as any..

in practice NTP doesn't care much what is in those 4 bytes AFAIK. You could try with different values and see what happens ...
(don't poll NTPservers more than once a minute, they don't like to be flooded.)

No, they're entirely arbitrary - except for the case of stratum 0, where some combinations of characters are used to rate limit clients... precisely related to your last line.

Personally, my NTP server broadcasts to the network once a minute, so as it stands, the arduino never has to request the time anyway.

Thanks for the replies guys.