BIND Configuration File Guide--include Statement

include path_name;

The include statement inserts the specified file at the point that the include statement is encountered. It cannot be used within another statement, though, so a line such as

acl internal_hosts { include "internal_hosts.acl"; };

Use include to break the configuration up into easily-managed chunks. For example:

include "/etc/security/keys.bind";
include "/etc/acls.bind";

could be used at the top of a BIND configuration file in order to include any ACL or key information.

Be careful not to type "#include", like you would in a C program, because "#" is used to start a comment.