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NTP Server Information

The Network Time Protocol (NTP) is a mechanism for synchronising the time on computers. When the full NTP implementation is used, it is capable of maintaining the same time on two computers with an accuracy of around 1-30 ms despite the varying delays in internet propagation. Further information about NTP can be obtained from the main ntp web site at www.ntp.org.

The MSL NTP servers are dedicated servers running FreeBSD with the time controlled using a 1 pulse per second from the HP5071A caesium atomic clock which is part of the New Zealand time standard. The time in the servers is typically stable with respect to the time in the caesium clock around 1 microsecond but the variability in the network delays limit the accuracy in remote clocks.

The servers are publicly available to all connections from within NZ. (Note: these servers only respond to ntp and "Simple network time protocol (SNTP) requests. They do not respond to "datetime" requests.

Any emails about the service should be directed to time@irl.cri.nz.

Using the servers

The servers are currently available to all users but serious users i.e. those for whom the time is important are asked to register their use of the server with MSL by sending the IP address of their server (a static address is required) and a contact email address to time@irl.cri.nz . The reason for this requirement is that some servers overseas have been flooded with requests from devices such as routers and we may need to restrict access to the server at some time in the future. Please limit your access to at most three servers and make any additional servers connect to what will be your three stratum 2 clocks.

The best and most accurate way of using this service is to install the official NTP distribution from http://www.ntp.org/. Versions are available for most versions of Unix. Windows versions are available for Windows NT, 2000 and XP.

Some information about common programs are listed below. Other programs may be found on the internet but please remember that they must use ntp or sntp not datetime or the NIST version of datetime.

If you are using SNTP then please use the address msltime.irl.cri.nz. This may be used on a round robin basis to share the load between the 2 servers.

The complete NTP distribution for either Unix or Windows

This is not intended to be a complete description about configuring NTP. You should consult the official documentation at www.ntp.org or the "NTP FAQ". This section simply includes a few tips which may be of use. To make your server get its time from the MSL server, enter into the ntp.conf file the line

server msltime1.irl.cri.nz
or
server msltime2.irl.cri.nz

Type the command "ntpdate msltime.irl.cri.nz". This will make an initial adjustment of the computer clock. If the computer clock is initially a long way off, it may be advisable to run this program several times. Then start the ntp daemon. After several minutes, run the command "ntpq -c pe" to check that ntpd program is running correctly. The response should be something like this

command "ntpq -c pe"

The "reach" column should be greater than 0 and should increase with time (patience is good with ntp) to eventually reach 377 which is as high as it goes. The offset and jitter should not be 0.0000. In case of problems, consult the system log file to see if the program has written an error message.

Note: You will probably need to configure some other options including adding additional servers for reliability in "ntp.conf" but these are beyond the scope of this brief note. See the official documentation or some other ntp document on the web.

NTP on Windows NT Servers

In the Windows NT Server resource kit is a program called TimeServ.exe. This can set the server time using NTP and may be the easiest way to synchronise an NT server. Information about TimeServe can be found here. Simply enter the msltime.irl.cri.nz in the NTP section of "timeserv.ini" and start the service as described in the documentation. Note the references to MSL in the documentation refer to the computer dial-up service not the ntp server.

NTP on Windows 2000, XP and Vista

The timeserve program was replaced in later versions of Windows with a program called "WTime32" and is available in the professional versions of 2000 and both versions of XP. This program can be set to automatically update the clock by connecting to an ntp server at periodic intervals. To make the program query the MSL server right click on the time in the taskbar (or select "Date and Time) in the control panel). Select the internet time tab in the "Date and Time Dialog" box and enter "msltime.irl.cri.nz" as the server. Click the "Update Now" button to test the connection. Future updates will occur at regular intervals to correct the computer clock. Click on the "time syncronization" link in the "Date and Time" dialog box for more information.

Note: If you are logged into a windows domain this does not work as the time on your computer is set by the domain and the internet time tab does not appear.

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