<listitem><para>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-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.</para></listitem>

<listitem><para>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

<varname>NTP=</varname> 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.</para></listitem>

<listitem><para>Maximum acceptable root distance. Takes a time value (in seconds).

<listitem><para>The minimum and maximum poll intervals for NTP messages.

Each setting takes a time value (in seconds).

<varname>PollIntervalMinSec=</varname> must not be smaller than 16 seconds.

<varname>PollIntervalMaxSec=</varname> must be larger than <varname>PollIntervalMinSec=</varname>.

<varname>PollIntervalMinSec=</varname> defaults to 32 seconds, and

<varname>PollIntervalMaxSec=</varname> defaults to 2048 seconds.</para></listitem>

<listitem><para>Specifies the delaying attempts to contact servers after network is online. Takes a time value (in seconds).

Defaults to 30 seconds and must not be smaller than 1 seconds.</para></listitem>