The Time of Internet

Fabrizio Pollastri
Information and curios, news and notions, Internet sites and services about time measurement, available also in italian. Since 1996 March 14, copies were requested.

All about the diffusion of Internet time services by IRITI and much about time measurement activities in the world can be found here as a collection of Internet sites and services. To face the subject from the beginning, it is useful the guided tour to time measurement.

Time Services by IRITI
  1. Right time
    1. accuracy
    2. update
    3. format
  2. NTP primary server
    1. characteristics
    2. how to synchronize
    3. who is already synchronized
    4. synchronization accuracy
  3. Network Time Protocol (NTP)
    1. working principles
    2. synchronization schemes
    3. what is needed
    4. NTP software
      1. Unix
      2. Windows 95
      3. Windows NT
      4. Windows for Workgroups

Time Sites and Services in the World

  1. Right times
  2. Synchronizations through Internet
  3. Synchronizations by navigation systems
  4. Telephone synchronizations
  5. Broadcasted synchronizations
  6. National authorities
  7. Legislation
  8. International organizations
  9. Other organizations
  10. Information about Earth rotation
  11. Tutorials
A Guided Tour to Time Measurement
  1. Solar Time
    1. true solar time
    2. mean solar time
    3. equation of time
  2. Time Zones
    1. meridian
    2. universal time
    3. time zones division
  3. Atomic Time
    1. atomic clock
    2. atomic second
    3. International atomic time
  4. Universal Coordinated Time
    1. Earth rotation slowdown
    2. leap second
  5. Legal Time
    1. primary standard of time
    2. time dissemination
    3. legal time winter/summer
    4. daylight-saving time in Italy
  6. Time Synchronization
    1. through Internet
      1. right times
      2. Network Time Protocol
      3. Time Protocol and Daytime Protocol
    2. other synchronizations
      1. navigation systems
      2. telephone
      3. broadcasted


a note from the author

I will be thankful to those people that will send suggestions, corrections and comments by e-mail to the address

I thank people and organizations that give out free of charge information and services on time measurement, on which this work is based.

The "Time of Internet" is a deep revision of the "Italian Standard Time " published on 1995 January on this same server. The structure and the contents are widely changed and extended. In addition, the integral english translation is available (the original work is in italian), it was not available in the previous edition. The english translation is very convenient to suit the international nature of the www system.

Though being the research activities at IRITI and mine in particular addressed to fields different from time metrology, in 1992 I started to work on same aspects of time measurement applied to Internet, driven by cultural curiosity and by environmental arguments.
The most important environmental argument is the site of IRITI that is in the same building of the Time and Frequency Laboratory of the National Electrotecnical Institute "G. Ferraris" that keeps the source of the italian standard time. Moreover, since over ten years, IRITI operates a computing system with a wide Internet connectivity that I manage as referee for all CNR units in Piedmont region.
Having all these ingredients at my disposal and seeing a lack on this matter in Italy, I gave in to the "temptation" of producing the result that can be found in these pages.

Have a good read.

Torino, 1996 March 5

F. Pollastri - The Time of Internet