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An Acronym for Network Time Protocol.

A method for synchronising a computer's internal clock (and system time) with an external source, such as a computer with a more accurate clock.

Machines that are synchronised with an atomic clock or GPS are stratum 1. Machines that synchronise to these machines are stratum 2, and so on. Normally stratum 1 machines aren't available for public connections.

Have a look at a the following page for a list of the stratum 1 time servers http://www.eecis.udel.edu/mills/ntp/clock1a.html . Or the following for a list of the stratum 2 time servers, http://www.eecis.udel.edu/mills/ntp/clock2a.html

NTP in NewZealand

Have a look at http://www.cosc.canterbury.ac.nz/research/reports/TechReps/1999/tr_9901.pdf for a scientific study (from 1999) of the topology of the country's main ntp servers. (A bit dated as GPS is much more widely available now).

Stratum 1 NTP servers

The Measurements Standards Laboratory at Inductrial Reasearch Limited run a HP5071A caesium atomic clock which is part of the New Zealand time standard. This server is avalible at the address msltime.irl.cri.nz, more details here

Clear generously provides a stratum 1 NTP server for public use:

  1. bigben.clix.net.nz

However, you really shouldn't synchronise to a stratum one server for your small network - if everyone did that then the the server would probably need too much bandwidth. Please read http://list.waikato.ac.nz/pipermail/nznog/2001-October/003705.html. The difference in accuracy between syncing to a stratum 1 server and a lower stratum server is negligible!

For example, read http://www.cs.wisc.edu/plonka/netgear-sntp/ - in summary, NetGear hard-coded a public NTP server into some of their consumer products, which eventually ended up using hundreds of Mbits/second of the university's bandwidth, even after they were forced to shut down the server.

Other NTP Servers

Some NewZealand ISPs have NTP servers for their customers:

  1. ntp.iprolink.co.nz
  2. ntp.iconz.co.nz
  3. tk1.ihug.co.nz to tk3.ihug.co.nz
  4. time.paradise.net.nz

or you could try querying your ISP's DNS servers with "ntp" or "ntp1".

Many of NewZealand's Universities also have public time servers such as:

  • ntp.public.otago.ac.nz (Please notify before using)
  • ntp.massey.ac.nz (Open Access, use DNS, changed IP recently and now hosted by two machines)

For a long time WaikatoUniversity had public NTP servers but no longer provides public access.

Your best bet for a small home or office network is to set your server to "nz.pool.ntp.org" or "pool.ntp.org", which will use DNS to choose one of the many servers now registered with that project.

Non-NZ servers

As mentioned above, pool.ntp.org is a round-robin DNS for many ntp servers. Try <2-letter country code>.pool.ntp.org.

If you live in Germany (or somewhere close by) you may want to try this list:

  • time1.rrz.uni-koeln.de
  • time2.rrz.uni-koeln.de
  • time3.rrz.uni-koeln.de
  • ts-1.rz.rwth-aachen.de
  • ntp1.t-online.de
  • www1.rrz.uni-koeln.de
  • hora.cs.tu-berlin.de
  • rustime01.rus.uni-stuttgart.de
  • rzfs2.rz.tu-bs.de
  • ns1.hrz.uni-giessen.de
  • ntp2-rz.rrze.uni-erlangen.de
  • mailbox.tu-berlin.de
  • ntps1-0.cs.tu-berlin.de
  • ntp0.fau.de
  • ntp1.fau.de
  • ntp2.fau.de
  • ntp3.fau.de
  • ptbtime1.ptb.de
  • ptbtime2.ptb.de

You might also want to look at a very extensive list of public German NTP servers or some other list of public servers on the internet.

See also:

Part of CategoryNetworking