text: The configuration file for a 4.9 or later server can have a control entry, called include , which allows you to insert a new configuration file into the current configuration file. This allows you to take a very large configuration file and break it into smaller pieces. The database files (for all BIND versions) allow two control entries: $ORIGIN and $INCLUDE . $ORIGIN changes the origin, and $INCLUDE inserts a new file into the current file. The database control entries are not resource records; they facilitate the maintenance of DNS data. In particular, these statements make it easier for you to divide your domain into subdomains: they allow you to store the data for each subdomain in a separate database file.
  With BIND , the default origin for the DNS database files is the second field of the primary or secondary statement in the version 4 named.boot file or the second field of the zone statement in the version 8 named.conf file. The origin is a domain name that is appended automatically to all names not ending in a dot. This origin can be changed in the db file with $ORIGIN . In the db file, $ORIGIN is followed by a domain name. (Don't forget the trailing dot if you give the full domain name!) From this point on, all names not ending in a dot have the new origin appended. If your name server (e.g., movie.edu ) is responsible for a number of subdomains, you can use the $ORIGIN entry to reset the origin and simplify the files. For example:
  When you specify the origin on the $INCLUDE line, it only applies to the particular file that you're including. For example, the comedy.movie.edu origin only applies to the names in db.comedy . After db.comedy has been included, the origin returns to what it was before $INCLUDE, even if there was an $ORIGIN entry within db.comedy .