Locating NTP stratum sources

While setting up some machines to use one of Penn State’s NTP sources, I was curious where their master time source was located. After reading a bunch of NTP documentation, I came across the ntptrace utility:

$ ntptrace -dv clock.psu.edu

DoTransmit(128.118.25.3)
DoTransmit to 128.118.25.3
ReceiveBuf(128.118.25.3, 128.118.25.3)
server 128.118.25.3, port 123
stratum 16, precision -16, leap 00
refid otc1.psu.edu delay 0.05704, dispersion 0.00000 offset 233.148443
rootdelay 0.00020, rootdispersion 0.44749, synch dist 0.44759
reference time:      c7acb55e.088e4755  Sun, Feb 26 2006 18:16:46.033
originate timestamp: c7acb95f.f156e264  Sun, Feb 26 2006 18:33:51.942
transmit timestamp:  c7acb876.c4037000  Sun, Feb 26 2006 18:29:58.765

DoTransmit(128.118.25.5)
DoTransmit to 128.118.25.5
ReceiveBuf(128.118.25.5, 128.118.25.5)
server 128.118.25.5, port 123
stratum 1, precision -29, leap 00
refid 'WWV' delay 0.03889, dispersion 0.00000 offset 233.022950
rootdelay 0.00000, rootdispersion 0.22423, synch dist 0.22423
reference time:      c7acb95d.72909aed  Sun, Feb 26 2006 18:33:49.447
originate timestamp: c7acb95f.de6d04e6  Sun, Feb 26 2006 18:33:51.868
transmit timestamp:  c7acb876.d3904000  Sun, Feb 26 2006 18:29:58.826

This nifty little utility will print the stratum for each source between the client and the master, and will also decode and print the contents of each NTP message (the NTP RFC describes how each timestamp is used to compute the offset ) it receives. This is some sweeeeet livin’!

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