Andy's Technotes Home

Network Time Protocol

Here is a basic description for NTP.

For all about NTP check out this F.A.Q. (Frequently Asked Questions)

Having all devices on the network consistantly on the 'real' time will help prevent/limit finger pointing, gives you precise references for troubleshooting, is an industry best practice from several angles, and is now so easily done that there is no real excuse to avoid it.
Note that almost all devices with an internal clock are no more accurate than a 5 dollar watch and their time will drift depending on temperature. At the molecular and atomic level, temperature and vibration are essentially synonymous, and all digital time keepers simply count the vibrations of a crystal or atom, so if the temperate varies, then so will the time. For more info on this or other time topics, just ask Andy

Win2K/NT4/Win9x and such can sync using third party tools such as:

http://nettime.sourceforge.net/
http://www.oneguycoding.com/netdate/ (looks like he hasn't been updating the product for a few years)
or just search tucows for NTP clients

NetWare 5 and higher has support for this built for this within the TimeSync function built in to the core operating system.
Make sure the server polling external NTP sources has its TimeSync parameter "Polling Interval =" set to 60000 or higher instead of the default 600. I would not go any higher than 600000 (almost a week) otherwise you will start getting large enough corrections at those times that it would be noticable if your system's clock is drifting quickly.
NetWare 5.1SP5 and higher are also trivial NTP servers that can be pointed to as an internal time source. Up to at least NetWare 6, some UNIX/Linux boxes are looking for more NTP data than NetWare provides so in those cases you may need to make those UNIX type systems the primary time servers on your network with NetWare pulling UNIX.

NW 3 & 4 can sync using a third party tools such as RDATA from;

http://www.MurkWorks.com/ select products, NetWare, Remote Date (RDate) NLM
make sure you set the /p option to at least 600. 1000 would be about ideal and seems to work well

Notes:

Many of the time sources will stop serving you if you query them too often, so make sure you set your NTP tool to only check the time once or twice a day. (One day is 86400 seconds)

Many organizations already have an internal reference that should be used instead of getting bothing the public time servers again. If the don't already have one, help them arrange this.

External references Andy has used:

You have to make sure TCP port 123 is open to the Internet for these to work.

An alternat that I just found to the static addresses in the table below are the NTP Pools

. list of a few known public NTP servers with IP addresses as of 2002-09-23

132.246.168.164	time.nrc.ca	Secondary (stratum 2)
128.100.103.17	tick.utoronto.ca	Secondary (stratum 2)
128.100.100.128	tock.utoronto.ca	Secondary (stratum 2)
199.212.17.34	ntp1.cmc.ec.gc.ca	Secondary (stratum 2)
128.46.143.95, 128.46.108.95, & others	molecule.ecn.purdue.edu	Secondary (stratum 2)
192.6.38.127	ntp-cup.external.hp.com	Primary (stratum 1)
131.216.1.101	cuckoo.nevada.edu	Secondary (stratum 2)

For other time sources see David Mill's great list at University of Delaware or Novell's TID 10011518

Please use the secondary time sources as much as possible, only use the primary's if you have the justification and know what you are doing in which case you problably don't need this page.
For more sources, do search with a tool like Google.com for the following key words "ntp stratum public servers"

NTP.org is another resourse of NTP info

For other Time related information, see the NRC WebClock and USNO.

For the only real Date and Time display standard, read up on the ISO8601 standard. For a drier reading there is w3.org's write up. Or for easier reading, both Jukka Korpela and Markus Kuhn have recommended write ups.