To slave your NTP daemon to an external source, you need to modify the ______ variable (alt: value or record) in your /etc/ntp.conf file.
Answer: server
Explanation/Reference:
From the man pages:
server For type s and r addresses (only), this command normally mobilizes a persistent client mode association with the specified remote server or local reference clock. In client mode the client clock can synchronize to the remote server or local reference clock, but the remote server can never be synchronized to the client clock.