| Computer Science and Software Engineering |  |
The Department of Computer Science and Software Engineering at the University of Canterbury New Zealand provide a Stratum 1 Network Time Protocol server for New Zealand. The NTP server is connected to Trimble Palisade GPS.
We are publicly listed at the home of the Network Time Protocol as the only New Zealand public NTP Primary (stratum 1) Time Server
NZ clock1.canterbury.ac.nz (132.181.10.44)
Location: Computer Science Department, University of Canterbury
Synchronization: NTP V4 primary (Trimble Palisade GPS), Sun/Sparc
Service Area: New Zealand
Access Policy: restricted to stratum-2 servers providing synchronization to local networks of ten or more hosts,by prior arrangement
Note: IP addresses are subject to change; please use DNS
Contact: Peter Glassenbury ( peter.glassenbury@canterbury.ac.nz)
Network Time Protocol is a protocol that used to synchronize computer clock times in a network of computers. NTP uses Coordinated Universal Time (UTC) (Formerly known as Greenwich Mean Time (GMT)) to synchronize computer clock times to a millisecond, and sometimes to a fraction of a millisecond.
Most systems have two clocks: one is the battery powered Real Time Clock (RTC) which keeps track of time when the system is turned off but is not used when the system is running. The other is the System clock which is a software counter based on the timer interrupt. It typically gets initialized from the RTC (or some other source) at boot time.
The two clocks will drift at different rates, so they will gradually drift apart from each other, and also away from the real time. The simplest way to keep them on time is to measure their drift rates and apply correction factors in software. Since the RTC is only used when the system is not running, the correction factor is applied when the clock is read at boot time.
The next step up in accuracy is to use a program like ntpd to read the time periodically from a network time server or radio clock, and continuously adjust the rate of the system clock so that the times always match, without causing sudden jumps in the system time.
(from Linux Documentation Project (ldp) mini-howtos Clock-html)
...and not to forget us, Computer Science and Software Engineering department of the University of Canterbury, New Zealand.
In order to ensure reliability, clients should operate with several different servers and avoid common points of failure. As a general rule, between three and five servers are sufficient, but they should be selected from different networks. No more than two clients per network should use the same server on another network; however, in order to simplify management of host configuration tables, many hosts on the same network may use the same (redundant) servers on the same network.
There are many scenarios where the above rules may not apply, especially large campus or corporate networks, clients with intermittent connectivity and security considerations, which are beyond the scope of this page. Additional information can be found at the NTP web site www.ntp.org and the NTP software documentation, project page and FAQ linked from there.
The list of primary (stratum 1) and secondary (stratum 2) designates the NTP time servers available for public access under stated restrictions. Each entry gives the country code, state (US only), host name, Internet address, approximate location and geographic coordinates (if available), synchronization source (stratum, type of radio or satellite receiver and host type), suggested service area, access policy (as notified) and responsible person name and e-mail address. Most servers indicate the NTP version as well. It is always wise to consult the DNS to verify host addresses, which are changed from time to time. When more than one address is given, preference should given to each in order.
(from NBS Special Publication 432 c/o David Mills (<mills@udel.edu >), Public NTP Time Servers