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doc: update FAQ

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Miroslav Lichvar 2016-11-28 16:42:31 +01:00
parent 6b3800cc94
commit 4fc6a1b424
1 changed files with 19 additions and 3 deletions
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doc/faq.adoc
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@ -148,9 +148,14 @@ network. It's better to use more than one server, three or four is usually
recommended as the minimum, so `chronyd` can detect servers that serve false
time and combine measurements from multiple sources.
If you have a network card with hardware timestamping supported on Linux, it
can be enabled by the *hwtimestamp* directive in the _chrony.conf_ file. It
should make local receive and transmit timestamps of NTP packets much more
accurate.
There are also useful options which can be set in the `server` directive, they
are `minpoll`, `maxpoll`, `polltarget`, `maxdelay`, `maxdelayratio` and
`maxdelaydevratio`.
are `minpoll`, `maxpoll`, `polltarget`, `maxdelay`, `maxdelayratio`,
`maxdelaydevratio`, and `xleave`.
The first three options set the minimum and maximum allowed polling interval,
and how should be the actual interval adjusted in the specified range. Their
@ -189,6 +194,16 @@ with local NTP server
server ntp.local minpoll 2 maxpoll 4 polltarget 30 maxdelaydevratio 2
----
If your server supports the interleaved mode, the `xleave` option should be
added to the `server` directive in order to receive server's more accurate
hardware or kernel transmit timestamps. When combined with local hardware
timestamping, a sub-microsecond accuracy may be possible. An example could be
----
server ntp.local minpoll 2 maxpoll 2 xleave
hwtimestamp eth0
----
=== What happened to the `commandkey` and `generatecommandkey` directives?
They were removed in version 2.2. Authentication is no longer supported in the
@ -376,7 +391,8 @@ to serve time to clients in the network which support the broadcast client mode
=== Can `chronyd` keep the system clock a fixed offset away from real time?
This is not possible as the program currently stands.
Yes. Starting from version 3.0, an offset can be specified by the `offset`
option for all time sources in the _chrony.conf_ file.
=== What happens if the network connection is dropped without using ``chronyc``'s `offline` command first?