Correct Time at UW
Why worry about time?
To varying extents, time is important to all of us. To an individual, it's important to get to classes and appointments on time. For computers, it can be important to have accurate times to properly synchronize logged events such as attempts to violate security policies. Experiments that are computer-controlled may need very accurate time to correlate observed events. Because time is important, we need a method to accurately obtain time, to set time on computers, and to keep it accurate.
In order to provide time service to the UW campus, IT has purchased an accurate time source which is based on the Global Positioning System (GPS). The time server itself will normally maintain proper time (Universal Coordinated Time, UTC) to within about 20 microseconds. This is called a primary time source, or "stratum 1" time server within the terminology of network time services.
This server provides time to several secondary systems which comprise secondary (Stratum 2) servers. These servers query our primary, as well as other network time servers, and normally maintain time to within 10 or 20 milliseconds of UTC. Within IT, these systems are chosen based on their high availability and reliability. The time is then hierarchically distributed to less-critical systems.
Windows systems set their time from the UWyo domain controllers or time.windows.com. Linux or UNIX systems can set their time using NTP and IT's Stratum 2 servers.
Network Time Protocol (NTP) is a network protocol, as are Telnet and FTP.
IT’s preferred Stratum 2 servers are called time1, time2, time3, and time4. Note: these are aliases (DNS CNAME records) so when you put these in your NTP configuration file, NTP will display the systems’ true names in the output of commands such as “ntpq –p”. If your own department or college has chosen to serve time to its systems, please refer to that server instead.