Need a Time Server?
If you have contacted us because you need a time server, you can use our servers subject to the contraints discussed below. We offer three stratum 1 servers for time-setting for sites off-campus, and a tier 1 server for Purdue users. Our stratum 1 servers are part of the NTP Pool, and that service may provide a good option if you need more or other time servers, in addition to (or in place of) our servers. Other servers are listed at the time servers site.
We provide three NTP servers for use inside and outside of Purdue University. These consist of one stratum 1 time server (CDMA-based) for any Internet users, and two additional stratum 1 servers (GPS-based) for any users. A fourth (GPS-based) server is for internal Purdue use.
The CDMA stratum 1 server (andromeda, alias tock and ntp4) is currently a donated EndRun Technologies Tempus LX™ CDMA-based server, which uses cell-phone timing signals as a time standard. The location of the CDMA-based server is such that we have an extremely strong signal.
The two GPS stratum 1 servers (caspak/darkcity alias tick) are donated Symmetricom™ TymServe™ model 2100LD servers that are no longer sold or supported by Microsemi. These were refurbished with donated N024 GPS upgrade boards provided by HEOL Design. (A third refurbished server is expected to be added sometime in 2nd quarter 2016.)
Our internal-to-Purdue GPS stratum 1 server (ntp3) is a donated Microsemi TimeProvider 5000.
We make no guarantees about this service. The servers may go down at any time, or become unreachable to users outside Purdue, although that is unlikely. We will try to maintain reasonable availability, but any service is provided on an "as is" basis as a courtesy. We make no warranties about the accuracy of the time signal beyond our good-faith belief that it is as accurate as can be achieved using our stock hardware and software.
If you wish to use our time servers, we ask that you observe the following:
For users ON THE PURDUE WEST LAFAYETTE CAMPUS only:
We request that you point your NTP requests at ntp3.itap.purdue.edu (GPS) and/or ntp4.itap.purdue.edu (CDMA). This will be the best connection (lowest delay and jitter) for almost all Purdue campus users. Both are stratum 1 servers.
Hosts in Computer Science are a special case, and they should reference ntp4.cs.purdue.edu (alias: tock.cerias.purdue.edu) as a time source.
There is no need to inform us or register to use these servers from on campus.
For users NOT AT PURDUE:
Please send email to email@example.com if you intend to use our time servers. Let us know which machine/domain will be involved, and an email address if we need to contact you. Connect to either tick.cerias.purdue.edu (GPS, 2 machines) or tock.cerias.purdue.edu (CDMA).
Use the DNS names of our servers rather than the IP addresses. The IP addresses may change without warning but the names will remain constant. If we need to change our servers for some reason, use of the DNS names instead of the IP addresses should make any such change transparent.
If you have a slow connection or long round-trip delay to our server, then pick another NTP server or establish your own level 1 server (see below). This will give you better time sync.
Instead of having multiple machines connect to our servers, establish your own stratum 2 or 3 server. Have a single machine connect to our servers to set its time, then have all your local machines use it as their time source. This should work better by reducing the aggregate overall network delay. It also reduces load on our servers!
Please do not overpoll our servers. That is, leave the frequency at which you check to something reasonable -- if your internal clock is so bad as to require a resync every few minutes, then you should get a better machine or your own time server!
Standard NTP suggests that a good onboard clock with appropriate NTP settings will settle into a pattern of polling about once every 1024 seconds (maxpoll = 10).
If you have need of authenticated time (using MD5, as defined in the NTP protocol) then we can exchange key information to enable this. Contact firstname.lastname@example.org. We currently do not have autokeying set up on any of the servers.
Establishing your own server
Our Stratum 1 servers come as rack-mountable units with an external antenna. This is generally easy to set up. CDMA units work from cell phone signals, so anywhere inside where there is a good cellphone signal is appropriate. GPS units require an antenna mounted outside with an unobscured view of the sky.
Our servers have generally been simple to set up and maintain, with some running for nearly a decade.
Establishing your own time server might be a good move, especially if you need a secure time source, because you can run it inside your firewall. Cost for a system is generally a few thousand dollars for US customers. Options are available to get more precise local clock crystals for times when the external time source is unavailable, but that adds expense. For more details, you can visit EndRun Technologies, HEOL Design, and Microsemi Corporation for a range of possible NTP and PTP timing solutions.
We gratefully acknowledge the generous support from EndRun Technologies, Microsemi Corporation, and HEOL Design, as well as their great engineering and support.
For More Information
Lots more information on NTP, including the latest software, is available at http://www.ntp.org/.
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