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 servers off-campus, and a tier-2 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 a set of NTP servers for use inside and outside of Purdue University. These consist of three stratum 1 time servers (GPS and CDMA-based) for any Internet users, and an additional stratum 2 server for internal Purdue users.

Two of the Tier I servers are on the same LAN, and the third server (Tier I) is in a different building on a different LAN, for fault tolerance.

We make no guarantees about this service. The servers may go down at any time, or become unreachable to users outside Purdue. 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.

Access as a client

If you wish to use our time servers, we ask that you observe the following:


For users NOT AT PURDUE:

Authenticated Time

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 ntp-request@cerias.purdue.edu. We currently do not have autokeying set up on any of the servers.

Establishing your own server

All the Stratum 1 servers we use come as rack-mountable units with an external antenna. They are generally easy to set up, although antenna placement is important: GPS antennas usually require outside placement with a clear view of most of the sky, although we have ours near the peak of a building attic. Antennas mounted outside also need lightning arrestors installed for safety purposes. CDMA units work from cell phone signals, so anywhere inside where there is a good cellphone signal is appropriate.

We have had a generally very good experience with our TymServe products (the products work out of the box, but we have had slow -- and not always complete -- responses to some of our technical questions). All the software was in place and required minimal configuration. These products sync to GPS satellite signals.

We recently added an EndRun Tempus LX server. This also was extremely easy to set up and run -- less than 10 minutes from out of the box to locked and serving a signal! The documentation is good, and the interface is simple. We are very pleased with this server, too. EndRun makes servers that provide a time signal from either GPS or CDMA signals; ours is a CDMA unit.

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 Symmetricom or EndRun Technologies.

For More Information

Lots more information on NTP, including the latest software, is available at http://www.ntp.org/.

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