In this episode of PING, APNIC’s Chief Scientist Geoff Huston discusses how Sweden built a national time distribution system and the nature of time in the modern Internet.

At the RIPE86 Meeting held in Rotterdam in May of this year, Karin Ahl, the CEO of Netnod presented a talk titled “How Sweden Built a World-Leading Time Network”

A central problem in time distribution on the Internet is firstly the lack of security inside the Network Time Protocol (NTP), and secondly the sources and reliability of the time information. The first problem is solved by using the newer Network Time Security (NTS) protocol which adds TLS, and the second by investment in reliable and strategically placed time distribution servers, which is the basis of the Swedish national time initiative.

Geoff attended the Netnod presentation and reflects on the complex and murky history of time, and the emergence of worldwide communities that coordinate both civil time (what the time of day is, in the world) and the nature of how time is measured (how a ‘second’ is defined, for example).

Geoff discusses historic and current attempts to standardise time measurements (such as UT1 and UTC) — with their inherent compromises — against Earth’s revolutions and rotations around the Sun. These measurements have become increasingly critical to modern technology, such as GPS.

Read more about NTP, NTS, and the time problem at the APNIC Blog and elsewhere online:

Watch Karin Ahl’s presentation at RIPE86 Rotterdam
RIPE 86 bites — what’s the time? (2023 Geoff Huston’s APNIC Blog write-up on the issues)
Network Time Security: new NTP authentication mechanism (2021 APNIC Blog by Martin Langer)
How do you know what time it is? (2020 APNIC Blog by Patrik Fälström)
Putting a stop to Internet Time Shifters (2019 APNIC Blog by Neta Rosen Schiff)
Is the Internet Running Late? (2018 APNIC Blog by Geoff Huston)
Steve Allan blogs on time (background reading)
Tony Finch blogs on time (background reading)


The views expressed by the featured speakers are their own and do not necessarily reflect the views of APNIC.
At the RIPE86 Meeting held in Rotterdam in May of this year, Karin Ahl, the CEO of Netnod presented a talk titled “How Sweden Built a World-Leading Time Network”

A central problems in time distribution on the Internet is firstly the lack of security inside the Network Time Protocol (NTP) and secondly the sources and reliability of the time information. The first problem is solved by use of the newer Network Time Security (NTS) protocol which adds TLS, and the second by investment in reliable and strategically placed time distribution servers, which is the basis of the Swedish national time initiative.

Geoff saw this presentation and reflects on the complex and murky history of how we “do” time, and the emergence of a worldwide communities which coordinate both civil time (what the time of day is, in the world) and the nature of how we measure time (what is a “second” exactly and how is it defined?)

Decisions made in the 1950s and 1970s to try and normalise the difference between monotonically increasing “UT1” time and the civil time system we know as “UTC” continue to plague the IT world, as civil time drifts (occasionally) by one second forwards (or very occasionally backwards) against UT1 -And with the emergence of more and more technology and especially satellite based systems like GPS, Bai-Dou, Galileo and GLONASS which provide time, the need to finalise the relative status of each time model becomes greater.

Read more about NTP, SNTP and the Time problem at the APNIC Blog and elsewhere online:

Watch Karin Ahl’s presentation at RIPE86 Rotterdam
RIPE 86 bites — what’s the time? (2023 Geoff Huston’s APNIC Blog write-up on the issues)
Network Time Security: new NTP authentication mechanism (2021 APNIC Blog by Martin Langer)
How do you know what time it is? (2020 APNIC Blog by Patrik Fälström)
Putting a stop to Internet Time Shifters (2019 APNIC Blog by Neta Rosen Sc