Pool Features

Modern sub micro seconds fail over time sources with clustered configuration in high availability configuration assures smooth clients operation. Pool has different DNS name space definitions depending of client capabilities. With specified DNS name reference server responses with corresponding IP communication protocol. All pools / servers features optional NTS secure time distribution.

Pool defined DNS names


This is general NTP v4 pool with dual stacked IPv4 and IPv6 connected servers. All servers are members of this pool. DNS name pool.chrony.eu is defined in IPv4 and IPv6 DNS name space.

general chrony.eu pool


This is general NTP v4 pool with IPv4 connectivity only. All servers are members of this pool. Suitable for legacy NTP client applications. DNS name pool4.chrony.eu is defined in IPv4 DNS name space only.

IPv4 chrony.eu pool


This is general NTP v6 pool with IPv6 connectivity only. All servers are members of this pool. Suitable for new IPv6 oriented NTP clients. DNS name pool6.chrony.eu is defined in IPv6 DNS name space only.

IPv6 chrony.eu pool

What they said about Network Time Protocol (NTP) and chrony.

  • Chrony is a versatile implementation of the Network Time Protocol (NTP). It can synchronise the system clock with Network Time Protocol servers, reference clocks (e.g. GPS receiver), and manual input using wristwatch and keyboard. It can also operate as a Network Time Protocol version 4 (RFC 5905) server and peer to provide a time service to other computers in the network. It is designed to perform well in a wide range of conditions.

  • NTP is intended to synchronize all participating computers to within a few milliseconds of Coordinated Universal Time. It uses the intersection algorithm, a modified version of Marzullo's algorithm, to select accurate time servers and is designed to mitigate the effects of variable network latency. NTP can usually maintain time to within tens of milliseconds over the public Internet, and can achieve better than one millisecond accuracy.

  • The NTP model includes a number of widely accessible primary time servers synchronized by wire or radio to national standards. The purpose of the NTP protocol is to convey timekeeping information from these primary servers to secondary time servers and clients via both private networks and the public Internet. Precisely tuned algorithms mitigate errors that may result from network disruptions, server failures, and possible hostile actions.

    IETF RFC5905


Principal configuration of CHRONY cluster:

Time servers and failover groups fetures:

Time servers features:

  • professional GPS timing modules
  • high gain antennas
  • nanosecond precision
  • support IPv4 and IPv6 (dual stack)
  • linux os
  • optional secure NTS distribution

Failover groups features:

  • fail-over groups with two servers
  • active / active fail over
  • failover convergence up to 50ms
  • load balancing
  • low delay optical connections
  • dual PPS sources

How to use

How to use chrony.eu NTP pool?

Short instructions how to setup your computer/device in few simple steps.

  • Linux
  • How to set chrony.eu NTP pool on Linux.
  • Windows
  • How to set chrony.eu NTP pool on Windows.
  • macOS
  • How to set chrony.eu NTP pool on macOS.
  • FreeBSD and other
  • How to set chrony.eu NTP pool on FreeBSD or other devices.

Screenshots of real time statistic.

We collect statistic of over 350 different sensors for each chrony NTP server. In that way we better understand our time servers. Here are some real examples of this statistical data.