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RE: Windows Time Synchronization - Best Practices
From: "Airey, John" <John.Airey () rnib org uk>
Date: Tue, 26 Oct 2004 13:10:21 +0100

-----Original Message-----
From: full-disclosure-admin () lists netsys com
[mailto:full-disclosure-admin () lists netsys com]On Behalf Of Andrew
Farmer
Sent: 25 October 2004 20:22
To: Gary E. Miller
Cc: Micheal Espinola Jr; full-disclosure () lists netsys com
Subject: Re: [Full-disclosure] Windows Time Synchronization - Best
Practices


On 24 Oct 2004, at 18:48, Gary E. Miller wrote:
On Fri, 22 Oct 2004, Micheal Espinola Jr wrote:
You can certainly have multiple time servers specified with Windows
Time Service (SNTP).  RTM.  It has the ability to failover 
through a
list.

Yes you can have multiple time servers, but only one active 
at a time.
With NTP your client polls a number of diverse servers.  Routes can
flap, servers can go wacko, but your time stays solid.

The canonical *NIX ntp client supports multiple active servers, if
that's what you're talking about.

No idea about Windows, though.

Getting back to the poster's original question, Windows is really bad
for time synchronisation. Whereas you can set an NTP server to
UTC/GMT/ZULU (or whatever other name you are going to call it), Windows
does indeed move the clock forward and backward. 

We've experienced this difficulty ourselves where you log in to a server
which then puts the clock an hour forward and then Windows itself puts
the clock an hour forward. The end result is that the clock is wrong.
Local time should simply be calculated as an offset from UTC. So instead
of changing the clock, change the time zone. Then it won't matter if the
time zone is changed to BST (for example) more than once. The clock and
the offset will stay the same.

Note to Microsoft - fix this stupidity in your next version of Windows.
It will annoy your users to begin with, but a number of time synch
issues will be solved in one fell swoop. All the three letter codes are
publicly available and understood by your end users.

-- 
John Airey, BSc (Jt Hons), CNA, RHCE
Internet systems support officer, ITCSD, Royal National Institute of the
Blind,
Bakewell Road, Peterborough PE2 6XU,
Tel.: +44 (0) 1733 375299 Fax: +44 (0) 1733 370848
John.Airey () rnib org uk 

Even if Embryonic Stem Cell Research yielded medical treatments, how
could enough eggs be obtained to make them viable? We can't even get
enough organs for transplant donation.

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