Useful time protocols

The Network Time Protocol (NTP) is a protocol for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks like Internet. The project is a big virtual cluster of timeservers providing reliable easy to use NTP service for millions of clients. Unfortunately NTP cannot be used everywhere without problems. NTP uses UDP on port 123 as its transport layer, and that could be blocked by the firewall in many places.

HTP Time Sync is one alternative way to get correct time to your computer. It uses the HTTP protocol for time synchronization. Every Web server runs HTTP and, by definition, Web servers always respond to HTTP requests with their current date and time. The current time and date information is available on the HTTP header text line that starts with text “Date:”.

You can use whatever suitable tools to write a simple script that gets that time (tip: you can connect to web server with nc or telnet instead of big bew browser software) or you can use ready made software you can find at HTTP Time Protocol / htpdate web page.



  1. Time Synchronisation says:

    Global Positioning System…

    Typically, GPS time servers can provide accuracy to within a few milliseconds (thousandths of a second) but a lot depends on a network layout. Time synchronisation can be affected by distance travelled and the speed machines process information…

  2. Ahmed Aurrichio says:

    I found this information interesting.

  3. Micah Morvay says:

    I found this information usefull.

  4. Elisabeth Dungey says:

    This is a great post.

  5. Timothy Koppel says:

    This is a usefull post.

  6. Tomi Engdahl says:

    Set your computer clock via the Internet using tools built into the operating system

    Most operating systems (i.e. Windows, Mac, Linux) have an option to automatically synchronize the system clock periodically using an NTP (network time protocol) server:

    Windows: Double-click the system clock and then click on the Internet Time tab.

    Mac: Applications > System Preferences > Date & Time

    Linux: System > Admin >Time and Date

    In the settings, you may be allowed to pick which NTP server the time comes from.
    NIST operates several stratum-1 network time servers, which means their time is directly linked to UTC(NIST), the official NIST time.

  7. tomi says:

    You have a nice blog on time synchronization issues.


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