Networking, The Campus Network Time Protocol Server

This page contains information about the campus Network Time Protocol (NTP) server (ntp.illinois.edu).

Technology Services provides Network Time Protocol (NTP) servers that can be used to synchronize the time of other computers on campus. After you configure your system to use ntp.illinois.edu, your system will resolve (randomly) to one of the three Technology Services Stratum-2 time providers.

Security Warning:

If you are a campus system administrator, you should ensure that any NTP servers on your network are not utilizing ntpd to serve time. Publicly accessible NTP servers running ntpd may be susceptible to being used in Distributed Denial of Service (DDoS) attacks.

See NTP (on the Technology Services Security Wiki space) for more information & instructions.

System administrators and NTP

For general information about NTP for system administrators, see the NTP Public Services Project website.

Mac and Windows operating systems and NTP

Configure your system to use ntp.illinois.edu.

  • Mac systems

    By default, Macs use Apple's time server. To achieve the best interaction with campus systems, you can set your Mac's clock to the campus NTP as follows:
    1. Under System Preferences, select Date & Time.
    2. Open the Date & Time tab.
    3. In the Set date and time automatically field, remove the Apple service and replace it with ntp.illinois.edu.
       

  • Windows systems (on a campus domain)

    Windows systems that are joined to a domain (e.g. UIUC or UOFI) already synchronize their clocks to a domain controller, and should not be manually reconfigured to use the Tech Services NTP servers.
     

  • Windows systems (non-domain): Changing to campus NTP

    If your Windows system is not part of a domain, you can set your computer's time to the campus NTP servers with the command
    net time /setsntp:ntp.illinois.edu
    NOTE: Users who who have personal firewall software may need to adjust their firewall's configuration to enable communication with an NTP server.

More about NTP

NTP is not the same as timed; timed uses a different protocol which our time servers do not support.

The three Stratum-2 machines set their own clocks accurately by referring to the campus Stratum-1 time source, which keeps time within about 20 microseconds of true UTC using a GPS receiver. GPS, the Global Positioning System, allows precise location of receivers anywhere on earth, and to do this the receivers must know exactly what time it is relative to the GPS satellites, so a useful side effect of precise GPS positioning information is that the receiver also gets to find out the exact time.

If there are applications on systems on campus that require time accurate to the sub-millisecond level, direct NTP peering with the Stratum-1 clock can be arranged; however for the vast majority of systems on campus, the time from the Stratum-2's is more than sufficient, resulting in a clock setting within ten milliseconds or so of the exact time.

If you're interested in general information on NTP, you can find an overview, history, the latest news, and other interesting references on the Network Time Foundation website.