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// Association options - included twice.
//
// Note, some of these options are described with special refclock
// semantics in includes/clock-options.adoc.
+bias+::
Add the command argument, a floating-point value in seconds, to the
time offset (θ) computed for this server; this may be useful if
you are a client on a network connection such as an ADSL line where
there is a predictable asymmetry between upstream and downstream
flight times. One way you might see this is if you use a fixed set
of others and one has a stable offset that is an outlier from the
others; in that case, you might want to use +bias+ to compensate out
the offset.
+burst+::
When the server is reachable, send a burst of eight packets instead of
the usual one. The packet spacing is normally 2 s; however, the
spacing between the first and second packets can be changed with the
calldelay command to allow additional time for a modem or ISDN call to
complete; this is designed to improve timekeeping quality with the
+server+ command.
+iburst+::
When the server is unreachable, send a burst of six packets instead
of the usual one. The packet spacing is normally 2 s; however, the
spacing between the first and second packets can be changed with the
calldelay command to allow additional time for a modem or ISDN call to
complete; this is designed to speed the initial synchronization
acquisition with the +server+ command, and when
{ntpdman} is started with the +-q+ option.
+key+ _key_::
All packets sent to and received from the server or peer are to
include authentication fields encrypted using the specified _key_
identifier with values from 1 to 65535, inclusive. The default is to
include no encryption field.
+minpoll+ _minpoll_::
+maxpoll+ _maxpoll_::
These options specify the minimum and maximum poll intervals for NTP
messages, as a power of 2 in seconds. The maximum poll interval
defaults to 10 (1,024 s), but can be increased by the _maxpoll_ option
to an upper limit of 17 (36.4 h). The minimum poll interval defaults
to 6 (64 s), but can be decreased by the _minpoll_ option to a lower
limit of 0 (1 s).
+mode+ 'option'::
Pass the +option+ to a reference clock driver. This option is valid
only with refclock addresses.
+noselect+::
Marks the server as unused, except for display purposes. The server is
discarded by the selection algorithm.
+prefer+::
Marks the server as preferred. All other things being equal, this host
will be chosen for synchronization among a set of correctly operating
hosts. See the "Mitigation Rules and the prefer Keyword" page
for further information.
+true+::
Mark the association to assume truechimer status; that is, always
survive the selection and clustering algorithms. This option can be
used with any association but is most useful for reference clocks
with large jitter on the serial port and precision pulse-per-second
(PPS) signals. Caution: this option defeats the algorithms designed to
cast out falsetickers and can allow these sources to set the system
clock. This option is valid only with the +server+ command.
+version+ _version_::
Specifies the version number to be used for outgoing NTP packets.
Versions 1-4 are the choices, with version 4 the default.
// end
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