The pool directive can be used to configure chronyd for a pool of NTP
servers (e.g. pool.ntp.org). The name is expected to resolve to multiple
addresses which change over time.
On start, a source will be added for each resolved address. When a
source from the pool is unreachable or marked as falseticker, chronyd
will try to replace the source with a newly resolved address of the
pool.
The minimum interval between replacements is currently set to 244
seconds to avoid frequent DNS requests.
