[Aavso-photometry] Internet Time Sync

Fri Apr 6 07:41:03 EDT 2007

Wolfgang, thanks, you hit the nail on the head. I was getting a message to
the effect that my computer was at least "one stratum behind," but I had no
idea what that meant. Clearly the stratum 1 servers that I was accessing
were restricting access. I did not know the relevance of stratum in time
sync services. The Odd thing is that the stratum 1 servers I was attempting
to access appear to be the default servers loaded by windows, at least I
didn't load them.

Your e-mail is a great reference.

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Subject: Aavso-photometry Digest, Vol 41, Issue 2

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Today's Topics:

   1. Re: Internet Time Sync (Wolfgang Renz)
   2. Re: Internet Time Sync (Roland Roberts)

----------------------------------------------------------------------

Message: 1
Date: Tue, 3 Apr 2007 23:26:40 +0200
From: "Wolfgang Renz" <w_renz at onlinehome.de>
Subject: Re: [Aavso-photometry] Internet Time Sync
To: "Tim Crawford" <tcarchcape at yahoo.com>
Cc: AAVSO-PHOTOMETRY <aavso-photometry at mira.aavso.org>
Message-ID: <001b01c77636$c597a5f0$0a01a8c0 at wrwinxppro>
Content-Type: text/plain;	charset="Windows-1252"

Hi Tim

Primary (stratum 1) and secondary (stratum 2) NTP time servers have
an access policy and therefore usually have at least voluntary restrictions
to avoid overloading them (if this happens, they might tighten their
restrictions or even stop their service):
   http://ntp.isc.org/bin/view/Servers/RulesOfEngagement

Stratum servers are intended to be used to synchronize other time servers.
They are NOT intended to be queried by single computers say every 10 min !
tick.usno.navy.mil and tock.usno.navy.mil are such primary stratum 1 time
servers that have a restricted access:
   http://ntp.isc.org/bin/view/Servers/RestrictedAccess
   http://ntp.isc.org/bin/view/Servers/TickUsnoNavyMil
   http://ntp.isc.org/bin/view/Servers/TockUsnoNavyMil
So its better to not use them for ordinary NTP users.

Here you can find all time servers.
NTP Home - NTP.Servers Web:
   http://ntp.isc.org/bin/view/Servers/WebHome
Public NTP Primary (stratum 1) Time Servers (intended to synchronise
secondary servers)
   http://ntp.isc.org/bin/view/Servers/StratumOneTimeServers
   http://www.eecis.udel.edu/~mills/ntp/clock1a.html
Public NTP Secondary (stratum 2) Time Servers (intended to synchronise
LANs/WANs)
   http://ntp.isc.org/bin/view/Servers/StratumTwoTimeServers
   http://www.eecis.udel.edu/~mills/ntp/clock2a.html
Public NTP Pool Time Servers (intended to synchronise computer clocks)
   http://ntp.isc.org/bin/view/Servers/NTPPoolServers
   Area:          HostName:                   PoolServers:
   Worldwide      pool.ntp.org                http://www.pool.ntp.org/zone/@
   Africa         africa.pool.ntp.org
http://www.pool.ntp.org/zone/africa
   Asia           asia.pool.ntp.org
http://www.pool.ntp.org/zone/asia
   Europe         europe.pool.ntp.org
http://www.pool.ntp.org/zone/europe
   North America  north-america.pool.ntp.org
http://www.pool.ntp.org/zone/north-america
   Oceania        oceania.pool.ntp.org
http://www.pool.ntp.org/zone/oceania
   South America  south-america.pool.ntp.org
http://www.pool.ntp.org/zone/south-america

To synchronise computer clocks one should use pool servers.
For these there exist also sub-zones by country:
   For the US see:
   http://www.pool.ntp.org/zone/us
These might be closer to you computer and therefore even have a shorter
ping round trip time than some stratum servers. 

If you still feel the need to query stratum time servers, please restrict
yourself
to use secondary stratum 2 time servers.

Clear skies
 Wolfgang

-- 
Wolfgang Renz, Karlsruhe, Germany
Rz.BAV = WRe.vsnet = RWG.AAVSO

----- Original Message ----- 
From: "Tim Crawford" <tcarchcape at yahoo.com>
To: <aavso-photometry at mira.aavso.org>
Sent: Tuesday, April 03, 2007 1:13 AM
Subject: [Aavso-photometry] Internet Time Sync

>I try to use one of the following two server sources,
> each time I observe:
>     tick.usno.navy.mil
>     tock.usno.navy.mil
> 
> These can be busy sources so if one is busy try the
> other; they are easy to add to your server list on the
> internet time tab of the date and time control panel.
> 
> Ad Astra
> 
> Tim Crawford  CTX
> Arch Cape Observatory

------------------------------

Message: 2
Date: Wed, 04 Apr 2007 00:58:41 -0400
From: Roland Roberts <roland at astrofoto.org>
Subject: Re: [Aavso-photometry] Internet Time Sync
To: aavso-photometry at mira.aavso.org
Message-ID: <46133081.8080604 at astrofoto.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Brad Walter wrote:
> My computer operating system is Windows XP Professional service pack 2.
Ever since I installed the Windows upgrade at the beginning of March for the
change in daylight saving time, I have not been able to synch to either the
NIST time server or the Windows Internet time server. I keep getting the
following error:
>   
You might want to try a look at this: 
http://www.timetools.co.uk/support/windows-xp-ntp-time-server.htm

I have the same version on Windows and I even set my system clock to UTC 
(dual Linux and Windows boot) and have had no trouble with the time.  I 
set the first two ntp hosts to be "local" based on the two networks I'm 
most commonly on followed by the pool servers the Wolfgang Renz discusses.

roland

-- 
                       PGP Key ID: 66 BC 3B CD
Roland B. Roberts, PhD                             RL Enterprises
roland at rlenter.com                            6818 Madeline Court
roland at astrofoto.org                           Brooklyn, NY 11220

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