[cifs-protocol] RE: Registry Setting to change NTP clients not to run as 'symmetric active'

Andrew Bartlett abartlet at samba.org
Sat Jun 14 12:51:20 GMT 2008

On Fri, 2008-06-13 at 12:52 -0700, Hongwei Sun wrote:
> Andrew,
>    Thank you for the feedback regarding Microsoft implementation of NTP client modes.
>    Actually, in Windows Behavior  of  [MS-SNTP], the section below describes how Windows clients set the Mode field.
> [MS-SNTP]  Windows Behavior <13>
> In Windows 2000, the client always sets the Mode field of its Client
> NTP Request messages to 0x3 ("Client"). In Windows XP, Windows Server
> 2003, Windows Vista, and Windows Server 2008, a client that is also a
> time source sets the Mode field of its Client NTP Request messages to
> 0x1 ("Symmetric Active"), while a client that is not a time source
> sets the Mode field in its Client NTP Request messages to 0x3
> ("Client"). By default, a client running on a domain controller is
> also a time source. The syntax and semantics for the Mode field of the
> Client NTP Request message are specified in [RFC1305] Appendix A.

However it does not note that this is inconsistent with all the RFCs in
this area.  Per my reading symmetric active should only be used between
active time servers (ie, with local GPS clocks), not by simple clients.

Furthermore, it breaks things, and causes people pain.  Isn't that
enough reason not to do it?  (I'm clearly barking up the the wrong tree
here.  What's the e-mail address for 'I think Microsoft screwed up'?)


Andrew Bartlett

Andrew Bartlett                                http://samba.org/~abartlet/
Authentication Developer, Samba Team           http://samba.org
Samba Developer, Red Hat Inc.                  http://redhat.com

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