Swedish Distributed Time Service

Welcome to the Swedish Distributed Time Service. This service delivers time over the Internet using NTP, and several other protocols upon request.

The service is owned by The Swedish Post and Telecom Authority (PTS), operated by Netnod, and monitored by RISE Research Institutes of Sweden.

There will be 5 time nodes distributed over Sweden. The time nodes are continously monitored and steered so that they follow UTC(SP). Each time node has two atomic clocks. Even if a time node would lose all contact with all its sources for time keeping, it is expected to be able to keep its time within narrow limits for months.

NTP service

The NTP service has two independent NTP servers in each time node.

The NTP servers are custom build hardware (FPGA cards) with 10Gb/s interfaces that can answer signed and unsigned NTP questions over both IPv4 and IPv6 at line-rate speed. The NTP server receives 1PPS and 10MHz signals from the local timescales which ensures a high accuracy of the NTP timestamps.

To use the NTP service, you can use the anycast address which will direct the client to the closest available server:

If you want to take your time from more than one server, you can use some or all of the unicast addresses:

The NTP service is free for use for anyone anywhere.

Operational Status Log

Other information


For more information about the service, please contact Netnod or The Swedish Post and Telecom Authority (PTS).

Network information

The NTP service uses the following IP networks and AS number:
IPv4: ...
IPv6: 2a01:3f7:0::/48 ... 2a01:3f7:7::/48
AS: 57021

This system also serves addresses from previous generation systems that should not be used for new installations.