os: time sync information

UPDATE: added some information regarding syncing to non-windows time sources.

i hate dealing with time synchronization. the tools for windows are so hokey. you know, little nuances like deprecating net time in favor of w32tm just doesn't get enough press. oh well. recently, i had to look through this stuff again. i decided i'd write up a little blog note as a reminder for myself the next time i have to look at this stuff. to start off with, very useful links.

how to turn on debug logging in the windows time service
how to configure an authoritative time server in windows server 2003
windows time server and internet communication
time synchronization may not succeed when you try to synchronize with a non-windows ntp server in windows server 2003

... and now, some very useful commands:

setting a time sync source:

w32tm /config /update /manualpeerlist:time.nist.gov time.windows.com /syncfromflags:MANUAL

verifying the settings:

w32tm /dumpreg /subkey:parameters

... following the commands above, if you're syncing time successfully, and you've turned on time sync debug logging as specified in the first link above, a successful entry in the log will look like the entry snippet below...

148232 19:09:40.0266456s - /-- NTP Packet: 
148232 19:09:40.0266456s - | LeapIndicator: 0 - no warning; VersionNumber: 3; Mode: 4 - Server; LiVnMode: 0x1C 
148232 19:09:40.0266456s - | Stratum: 2 - secondary reference (syncd by (S)NTP) 
148232 19:09:40.0266456s - | Poll Interval: 7 - 128s; Precision: -6 - 15.625ms per tick 
148232 19:09:40.0266456s - | RootDelay: 0x0000.1BFEs - 0.109344s; RootDispersion: 0x0000.CC68s - 0.798462s 
148232 19:09:40.0266456s - | ReferenceClockIdentifier: 0xC02BF412 - source IP: 192.168.1.1 
148232 19:09:40.0266456s - | ReferenceTimestamp: 0xC8FA05E75E673B78
148232 19:09:40.0266456s - - 12807313511368762700ns - 
148232 19:05:11.3687627s 
148232 19:09:40.0266456s - | OriginateTimestamp: 0xC8FA06F406D23EFC
148232 19:09:40.0266456s - - 12807313780026645600ns - 
148232 19:09:40.0266456s 
148232 19:09:40.0266456s - | ReceiveTimestamp: 0xC8FA06F406986261
148232 19:09:40.0266456s - - 12807313780025762700ns - 
148232 19:09:40.0257627s 
148232 19:09:40.0266456s - | TransmitTimestamp: 0xC8FA06F406986261
148232 19:09:40.0266456s - - 12807313780025762700ns - 
148232 19:09:40.0257627s 
148232 19:09:40.0266456s - >-- Non-packet info: 
148232 19:09:40.0266456s - | DestinationTimestamp: 
148232 19:09:40.0266456s - 0xC8FA06F406D23EFC
148232 19:09:40.0266456s - - 12807313780026645600ns
148232 19:09:40.0266456s - - 
148232 19:09:40.0266456s 
148232 19:09:40.0266456s - | RoundtripDelay: 000ns (0s) 
148232 19:09:40.0266456s - | LocalClockOffset: -882900ns - 0:00.000882900s 
148232 19:09:40.0266456s - \--

by default, time sync requests are sent in “symmetric active mode.” this works fine for windows servers but does not always work correctly for other non-windows ntp servers. instead, they favor “client mode.” in that case, your command would look like:

w32tm /config /update /manualpeerlist:mynonwindowstimesource.com,0x8 /syncfromflags:MANUAL

the 0x8 instructs the sync requests to send in “client mode” versus “symmetric active mode.”