kazulog@sv1:~$ for f in /etc/chrony/sources.d/ubuntu-ntp-pools.sources /etc/chrony/conf.d/ubuntu-nts.conf; do echo "===== $f"; sudo cat "$f" 2>/dev/null; done
===== /etc/chrony/sources.d/ubuntu-ntp-pools.sources
# Use NTS by default
# NTS uses an additional port to negotiate security: 4460/tcp
# The normal NTP port remains in use: 123/udp
pool 1.ntp.ubuntu.com iburst maxsources 1 nts prefer
pool 2.ntp.ubuntu.com iburst maxsources 1 nts prefer
pool 3.ntp.ubuntu.com iburst maxsources 1 nts prefer
pool 4.ntp.ubuntu.com iburst maxsources 1 nts prefer
# The bootstrap server is needed by systems without a hardware clock, or a very
# large initial clock offset. The specified certificate set is defined in
# /etc/chrony/conf.d/ubuntu-nts.conf.
pool ntp-bootstrap.ubuntu.com iburst maxsources 1 nts certset 1

# If you can't or won't use NTS, then here are the old NTP-only definitions

# This will use (up to):
# - 4 sources from ntp.ubuntu.com which some are ipv6 enabled
# - 2 sources from 2.ubuntu.pool.ntp.org which is ipv6 enabled as well
# - 1 source from [01].ubuntu.pool.ntp.org each (ipv4 only atm)
# This means by default, up to 6 dual-stack and up to 2 additional IPv4-only
# sources will be used.
# At the same time it retains some protection against one of the entries being
# down (compare to just using one of the lines). See (LP: #1754358) for the
# discussion.
#
# About using servers from the NTP Pool Project in general see (LP: #104525).
# Approved by Ubuntu Technical Board on 2011-02-08.
# See http://www.pool.ntp.org/join.html for more information.
#pool ntp.ubuntu.com        iburst maxsources 4
#pool 0.ubuntu.pool.ntp.org iburst maxsources 1
#pool 1.ubuntu.pool.ntp.org iburst maxsources 1
#pool 2.ubuntu.pool.ntp.org iburst maxsources 2
===== /etc/chrony/conf.d/ubuntu-nts.conf
# This CA is needed for the Ubuntu NTS bootstrap servers.  It has a very large
# validity range (decades into the past and future) to allow systems with a
# very large initial clock drift to use NTS.
# If there is already another certificate set using the same index as this one
# here ("1"), then this CA will get added to that set.
ntstrustedcerts 1 /etc/chrony/nts-bootstrap-ubuntu.crt