Usage means correcting the clocks of one or several workstations by referring to hosts on your local network or on the Internet. The kind of usage of this and other NTP services depends on your needs and some restrictions.

If you only want to have correct time stamps on files, e-mails, and news articles, it will be sufficient to call a simple client program at boot time and/or regularly. Precision of time on your machine will still be better than one second.

Windows 2000 or XP users in an enterprise or campus network don't need to know anything about time synchronization, assumed their network administrator has set up an authoritative time server. Users of older MS Windows versions may call
net time /domain:DOMAIN_name /set /yes or
net time \\timehost /set /yes
in an autostart or logon script (batch file). timehost is the NetBIOS name of some host on the local network having correct system time. Programs mentioned below in the 'MS Windows' section can do even more for you. They might set the clock more accurately, set it at startup, regularly, or on network dial-up.

Under Unix, call a clock synchronization program from a boot script and/or from crontab (every day or hour). You may use the ordinary Time service or the ntpdate program from the ntpd distribution (see below). It is delivered ready-to-run with most modern Unixes.

Internal users (in our campus network) should refer to one of our distribution servers (see the NTP subnet page). All users accessing a timing host fairly seldom may use our reference servers tick, tock and tack. Conversely, that means that external users should refer to our servers only infrequently or themselves set up a NTP subnet.

We would be glad to let our stratum-2 servers peer with yours, what would give you a clock accuracy better than ±10 milliseconds. If you are seriously concerned in very precise timekeeping, you will need a stratum-1 server requiring some primary source of legal time like GPS or DCF77. Look around on this site for some basic information.

In any case, if you intend to set up a NTP subnet of your own, you should read the page about the realization of our NTP service to use it as a template. Read on for instructions to set up several workstations with reasonable clock accuracy.

For a Unix or Linux machine you should use the original ntpd software. It is shipped along with most modern Unix variants (e.g. Solaris and AIX), though sometimes in an out-dated version. So you better get a copy of the distribution archive. You may download the old xntpd version 3 we are still using from this server. Better you get the latest version from the 'Home of the Network Time Protocol'. The file size is about 1.9 MB.

Unpack the archive file using gzip and tar to install all files in an own subdirectory tree. There will be a directory named html containing the complete ntp documentation. You must read the 'Building and Installing the Distribution' page on your machine. The old version is on this server and the latest version at the 'Home of the Network Time Protocol'.

After checking the prerequisites configure and compile from the root of the ntp subdirectory tree. You should be 'root' doing this for some reasons:
# configure --disable-debugging \
--disable-all-clocks
# make
# make install
The ntpd daemon and some utilities are now installed in /usr/local/bin.

Make sure that ntp is associated with 123/udp, not tcp, in the /etc/services file. Some Unixes (AIX) were formerly wrong about that point.

Create /etc/ntp.conf containing one line:
server kim.rz.fh-augsburg.de
or what your server is. That's the bare minimum. You better have a real configuration file.

If you mentioned the local clock as a peer in the /etc/ntp.conf file, it will be ruled by the ntpd daemon. Otherwise make an entry in /etc/crontab to call
clock -wu
every hour or so. This will set the internal (hardware) clock to correct time. Leave the -u off if your system clock is running at local time (not UTC).

Install a script to start and stop the ntpd daemon in your system startup directory (rc.d or what you have) to automatically handle it while booting and halting. It's slightly different for a Bourne shell and for a Korn shell.

You may get some suggestions from Stephan Seidl's NTP installation guide for Dresden Technical University (unfortunately no longer available) or from the NTP cookbook of University of Michigan.

Internal clients may use the campus NTP broadcast service. To get the necessary authentication keys you have to contact the operator of this service.

In a MS Windows 2000 or XP network, there is an integrated time client-server hierarchy based upon SNTP. Only one authoritative server in an enterprise network should refer to an external SNTP server. Server administrators should go to the Microsoft Support Server and search the Searcheable Knowledge Base for the keyword SNTP to get more information. You will be advised to inspect the help text for the net time ... command (call net time /?).

The ntpd software may be installed as a Windows service, but it would pay only as a NTP server installation. You wouldn't get very accurate time anyway under Windows NT since it is a not so good timekeeper (at least compared to other operating systems).

There are many good and simple client programs for Microsoft Windows, both shareware or freeware. Network time service clients for all versions of MS Windows are available. Most of them use the Simple Network Time Protocol (SNTP) which is sufficient for normal time accuracy needs. Some are even aware of connecting to the Net by dial-in and synchronize at that moment.

There is a category 'Windows > Internet > Time Synchronizers' on the nearest TUCOWS server. Select one and try on your own. Installation and setup of these programs is quite straightforward.

Even more client programs can be found via the 'Home of the Network Time Protocol'.

We for our former pool of PCs under MS Windows NT chose the TimeSync client written by Raju Varghese. It not only sets very accurate time, but also can run as a Windows NT service (like a Unix daemon). Moreover, it's free for educational institutions like us. If you find that interesting: There are comprehensive instructions how to use it and who may use it.

There's one special advantage using TimeSync: It is able to fetch its configuration parameters from a server. On all clients, TimeSync is installed equally and will get a parameter file from a server at every start-up. The file may be changed, affecting all clients at once.

Apple Macintosh users should look at the NIST Internet Time Service software list if they have MacOS or consult the manuals if they run OS X.

If you are (still) a DEC VMS user you can install the original ntpd daemon on your VAX system. Consider setting it up as a NTP server since the DEC machines are said to have good internal clocks.

CISCO routers may be able to serve as NTP peers. Please consult the manual, I don't know much (nearly nothing) about these boxes.

There's a WWW page by David Schwartz from where you can check your NTP server unless it's configured to block out external queries (e.g. restrict ignore).

Remember to configure your operating system for the correct time zone and daylight saving time regulations. Such settings are not part of NTP.