timesyncd.conf, timesyncd.conf.d — Network Time Synchronization configuration files
These configuration files control NTP network time synchronization. See systemd.syntax(5) for a general description of the syntax.
The default configuration is defined during compilation, so a
configuration file is only needed when it is necessary to deviate
from those defaults. By default, the configuration file in
/etc/systemd/ contains commented out entries
showing the defaults as a guide to the administrator. This file
can be edited to create local overrides.
When packages need to customize the configuration, they can
install configuration snippets in
/usr/local/lib/systemd/*.conf.d/. Files in
/etc/ are reserved for the local
administrator, who may use this logic to override the
configuration files installed by vendor packages. The main
configuration file is read before any of the configuration
directories, and has the lowest precedence; entries in a file in
any configuration directory override entries in the single
configuration file. Files in the
configuration subdirectories are sorted by their filename in lexicographic
order, regardless of which of the subdirectories they reside in. When
multiple files specify the same option, for options which accept just a
single value, the entry in the file with the lexicographically latest name
takes precedence. For options which accept a list of values, entries are
collected as they occur in files sorted lexicographically. It is recommended
to prefix all filenames in those subdirectories with a two-digit number and
a dash, to simplify the ordering of the files.
To disable a configuration file supplied by the vendor, the
recommended way is to place a symlink to
/dev/null in the configuration directory in
/etc/, with the same filename as the vendor
The following settings are configured in the "
A space-separated list of NTP server host names or IP addresses. During runtime this list is combined with any per-interface NTP servers acquired from systemd-networkd.service(8). systemd-timesyncd will contact all configured system or per-interface servers in turn until one is found that responds. When the empty string is assigned, the list of NTP servers is reset, and all assignments prior to this one will have no effect. This setting defaults to an empty list.
A space-separated list of NTP server host
names or IP addresses to be used as the fallback NTP servers.
Any per-interface NTP servers obtained from
take precedence over this setting, as do any servers set via
NTP= above. This setting is hence only used
if no other NTP server information is known. When the empty
string is assigned, the list of NTP servers is reset,
and all assignments prior to this one will have no effect.
If this option is not given, a compiled-in list of NTP servers
is used instead.
Maximum acceptable root distance. Takes a time value (in seconds). Defaults to 5 seconds.
The minimum and maximum poll intervals for NTP messages.
Each setting takes a time value (in seconds).
PollIntervalMinSec= must not be smaller than 16 seconds.
PollIntervalMaxSec= must be larger than
PollIntervalMinSec= defaults to 32 seconds, and
PollIntervalMaxSec= defaults to 2048 seconds.