Explanation
The rndc sub command that can be used in conjunction with the name of a zone in order to make BIND reread the content of the specific zone file without reloading other zones as well is reload. The reload sub command instructs the BIND server to reload the specified zone or all zones if no zone is specified. The reload sub command is useful for applying changes made to the zone files without restarting the BIND service or affecting other zones. The syntax of the reload sub command is as follows:
rndc reload [zone [class [view]]]
For example, to reload the zone example.com in the IN class and the default view, use the following command:
rndc reload example.com IN
References:
rndc - man pages section 8: System Administration Commands, sub command "reload"
17.2.3. Using the rndc Utility - Red Hat Customer Portal, section "Reloading the Configuration and Zones"