[ntp:questions] Windows Time with NTPv4

Ryan Malayter malayter at gmail.com
Mon Mar 10 16:15:27 UTC 2008


I let the trace run a bit longer. When configured with only an IP
address (and not the 0x8 client-mode identifier), here is the Vista
behavior. It appears to stick with symmetric-active mode, and
immediately goes to a poll interval of 1024 seconds:

Configured with IP address or hostname only:
Time (s)   behavior
--------    --------
0           w32tm /configure /manualpeerlist:10.140.84.147 /
syncfromflags:MANUAL /update
0           restart w32time
0.1				  NTPv3 client-mode query
0.1				  NTPv3 server-mode reply
1.5         NTPv3 symmetric-active mode query
1.5         NTPv3 symmetric-active mode reply
1025.5  		NTPv3 symmetric-active mode query
1025.5  		NTPv3 symmetric-active mode reply

The weird thing is that I get a monlist entry for the client in
symmetric active mode, even though I have this restrict configuration
in my ntpd config:
    restrict default kod nomodify notrap nopeer
    restrict 127.0.0.1

When w32time is explicitly configured to use a client-mode
association, I see similar behavior, but no symmetric mode
associations:
Time (s)   behavior
--------    --------
0           net start w32time
0.1         NTPv3 client-mode query
0.1         NTPv3 server-mode reply
1.5         NTPv3 client-mode query
1.5         NTPv3 server-mode reply
1025.5  		NTPv3 client-mode query
1025.5  		NTPv3 server-mode query

ntpdc monlist reports a mode 3 association with the Vista client in
this case.

So it appears the Windows Time Service behavior on Vista is "try
symmetric mode if I'm not told otherwise, and stick with that if it
works".




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