What is the difference between chronyd and ntpd?

I know that ntpd can gradually adjust the time so that it can converge gradually to the the reference clock. Can this be done with chrony?

  • Please rephrase that in English. As for the difference, chronyd is an evolution of ntpd, and generally performs better and smoother both for frequent and high-accuracy clock drifts.
    – Dani_l
    Oct 26, 2015 at 15:04
  • There is no one and only "ntpd", you have to be specific what server implementation you mean.
    – phk
    Oct 26, 2015 at 15:48
  • I corrected my English. About implementation, let will be RHEL (CentOS, Fedora).
    – ComBin
    Oct 26, 2015 at 19:20
  • 2
    @Dani_l do you have a reference for that claim, please? I've not previously heard of chronyd being more reliable than ntpd so I'd like to check out my options. Oct 26, 2015 at 20:29
  • @roaima chronyd is not more reliable, but chronyd can adjust in situations where ntpd can't perform well (such as intermittent internet connections) and from experience can hold better accuracy where high precision is required (a clock with high drift that required at most 1 second diff at all times - ntpd had to be run with cron on a minute by minute basis (the best resolution cron provides), chronyd handled that better)
    – Dani_l
    Oct 27, 2015 at 5:42

2 Answers 2


This site comparing chronyd vs ntpd vs openntpd suggests that chronyd has more flexibility in configuring a slewing settings.

  • 2
    I just want to point out the comparison table may be biased. One should consider the source Jan 23, 2019 at 21:34
  • 1
    Could be. You could always provide other sources.
    – Lee
    Jan 23, 2019 at 21:45

The Red Hat documentation here has a good comparison of Chrony and NTP and says "Chrony should be preferred for all systems except for the systems that are managed or monitored by tools that do not support chrony, or the systems that have a hardware reference clock which cannot be used with chrony."

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