In pool.ntp.org: How do I setup NTP to use the pool? the ‘server’ directive is still documented. May I suggest to change that into ‘pool’ directive? Or to at least mention that as the preferred method with ‘server’ as an alternative? The ‘pool’ directive has been supported since NTP 4.2.6, which was released already around 2009 or so (current stable release is 4.2.8p15) with improvements in 4.2.7p22 back in 2010. It has been working well ever since and has some advantages over the ‘server’ directive, as is clearly explained here:
https://kb.meinbergglobal.com/kb/time_sync/ntp/configuration/ntp_pool_usage
and
https://lists.ntp.org/pipermail/questions/2010-April/026304.html