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-rw-r--r--docs/configuration/service/ntp.rst31
1 files changed, 30 insertions, 1 deletions
diff --git a/docs/configuration/service/ntp.rst b/docs/configuration/service/ntp.rst
index 08be047c..e7ee392b 100644
--- a/docs/configuration/service/ntp.rst
+++ b/docs/configuration/service/ntp.rst
@@ -81,4 +81,33 @@ Configuration
.. cfgcmd:: set service ntp vrf <name>
- Specify name of the :abbr:`VRF (Virtual Routing and Forwarding)` instance.
+ Specify name of the :abbr:`VRF (Virtual Routing and Forwarding)` instance.
+
+.. cfgcmd:: set service ntp leap-second [ignore|smear|system|timezone]
+
+ Define how to handle leaf-seonds.
+
+ * `ignore`: No correction is applied to the clock for the leap second. The
+ clock will be corrected later in normal operation when new measurements are
+ made and the estimated offset includes the one second error.
+
+ * `smear`: When smearing a leap second, the leap status is suppressed on the
+ server and the served time is corrected slowly by slewing instead of
+ stepping. The clients do not need any special configuration as they do not
+ know there is any leap second and they follow the server time which
+ eventually brings them back to UTC. Care must be taken to ensure they use
+ only NTP servers which smear the leap second in exactly the same way for
+ synchronisation.
+
+ * `system`: When inserting a leap second, the kernel steps the system clock
+ backwards by one second when the clock gets to 00:00:00 UTC. When deleting
+ a leap second, it steps forward by one second when the clock gets to
+ 23:59:59 UTC.
+
+ * `timezone`: This directive specifies a timezone in the system timezone
+ database which chronyd can use to determine when will the next leap second
+ occur and what is the current offset between TAI and UTC. It will
+ periodically check if 23:59:59 and 23:59:60 are valid times in the
+ timezone. This normally works with the right/UTC timezone which is the
+ default
+