On Mon, Apr 18, 2016 at 10:14:20AM +0200, Rob Janssen wrote:
> Miroslav Lichvar wrote:
> >Yes, it seems request to the NIST servers have an extra 60 ms delay,
> >which makes them appear to run 30 ms ahead of UTC.
> >
> >In my logs it started approximately in October last year and it wasn't a
> >sudden switch, but rather a slowly increasing percentage of requests
> >getting this delay, which got close to 100% by the end of the year.
> >
> 
> Maybe they are overloaded?

Could that create a constant delay? If the network or the servers were
overloaded, I'd expect the extra delay to be randomly distributed
across some range. From the (limited) data I have it looks like the
distribution of the delay just shifted by ~63 milliseconds, there is
nothing in between. It would be interesting to see a traceroute to the
servers, or at least see if the delay affects also ICMP packets, but
they are being dropped somewhere on the path.

BTW, there was a very interesting report published recently about the
NIST NTP servers.

http://nvlpubs.nist.gov/nistpubs/jres/121/jres.121.003.pdf

-- 
Miroslav Lichvar
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