-# pool.ntp.org maps to more than 300 low-stratum NTP servers.
-# Your server will pick a different set every time it starts up.
-# *** Please consider joining the pool! ***
-# *** <http://www.pool.ntp.org/join.html> ***
-server 0.debian.pool.ntp.org iburst
-server 1.debian.pool.ntp.org iburst
-server 2.debian.pool.ntp.org iburst
-server 3.debian.pool.ntp.org iburst
+# pool.ntp.org maps to about 1000 low-stratum NTP servers. Your server will
+# pick a different set every time it starts up. Please consider joining the
+# pool: <http://www.pool.ntp.org/join.html>
+server 0.debian.pool.ntp.org iburst dynamic
+server 1.debian.pool.ntp.org iburst dynamic
+server 2.debian.pool.ntp.org iburst dynamic
+server 3.debian.pool.ntp.org iburst dynamic
+
+
+# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for
+# details. The web page <http://support.ntp.org/bin/view/Support/AccessRestrictions>
+# might also be helpful.
+#
+# Note that "restrict" applies to both servers and clients, so a configuration
+# that might be intended to block requests from certain clients could also end
+# up blocking replies from your own upstream servers.