NTP100 – Rev 2.2.0 Oct-12
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NTP Client Information
Any computer system desiring to synchronize its time to the NTP100 server must incorporate an NTP/SNTP client. A
NTP/SNTP client is responsible for asking the NTP server for time/date information, or in some cases simply listening on the
network for NTP time broadcasts, then setting the internal time of the computer or device. NTP client applications come in a
variety of offerings, supporting different features, and with different levels of accuracy, fault tolerance, and reporting. Many
are inexpensive to license, or free. A listing of NTP/SNTP clients can be found at the NTP home page, http://www.ntp.org,
as well as many shareware/freeware file search engines. A partial list is found below:
Dimension 4
Operates in most Windows environments. Concise user interface, can be minimized to the system tray. Can also be run as a
service. http://www.thinkman.com/
TimeSync
Operates in a Windows NT/2000 environment, and can run as a service. http://www.intsoft.com
XNTP
XNTP is the commonly used Unix distribution of NTP server/client software. XNTP is distributed with many Unix
operating system packages, and is licensed for use without fee. The distribution can also be built for Windows operating
systems although it is generally not needed for the Windows 2000/XP platforms (see Win32Time below). http://www.ntp.org
W32Time Service (Windows Time Service)
The Windows Time service is supplied with the Windows operating system and is typically active (started or running) by
default. W32Time is started by default on Windows XP and Windows Server 2003 machines regardless of whether they
belong to a workgroup or a domain. On Windows 2000 , W32Time must be manually started on machines belonging to a
workgroup.
The Windows Time service is designed to loosely synchronize (or set) the system time and allows for a 20 sec variance
between machines on a WAN or enterprise level ,and up to about 2 seconds at a local level (LAN). In addition, the system
time (network time) may not be accurate time relative to the UTC reference. In many applications, this type of inaccuracy is
not acceptable. The default poll times are often extended allowing for significant drift.
In general, most 3
rd
party SNTP or NTP client applications or services designed to run under Windows will disable (or
attempt to disable) the W32Time service. This is to allow for a more accurate system clock pointing directly to one or more
time servers and allowing a higher polling rate. If the Windows Time service is not disabled, this may cause undesirable
results with other applications or services which attempt to set the system time accurately. However, for certain network
configurations the user may be required to continue to use the Windows Time service. In such cases, the W32Time registry
entries will require modification from the default settings to achieve synchronization with the NTP100, within the framework
of the W32Time service capabilities.
A dissertation on configuring and deploying Win32Time in an enterprise network environment using an Authoritative Time
Server , Primary Domain Controller, Secondary Domain Controllers, or an Active Directory environment is beyond the
scope of this manual, and the support provided by Masterclock.
For suggestions on using the W32Time service, please see the troubleshooting area of this manual , as well as the appropriate
knowledgebase articles available at the Microsoft support site. Please also refer to the documentation included with your
Windows operating system for details. The Microsoft Knowledge Base also contains a number of other useful articles
regarding the W32Time service. Search on the ‘net time’ , ‘w32time’ , ‘symmetric active’ , ‘authoritative time source’, and
‘trusted time source’ keywords.
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