You want to configure a name server as a slave for all of the zones your primary master name server is authoritative for.
Add zone statements of type slave to correspond to all of the zone statements in your primary master name server's named.conf file. You can even use the primary master name server's named.conf file as a starting point, changing master to slave in each type substatement and adding masters substatements, specifying the master's address. You may also want to change the filename in the file substatement.
Many new administrators expect BIND to support a single configuration statement that says, "Run as a slave name server for all of the zones this other name server is authoritative for." Unfortunately, no such statement exists; a name server is configured as authoritative for zones on an individual basis.
Converting a primary master's named.conf file into a named.conf file appropriate for a slave is a piece of cake, though. In fact, I wrote a short Perl script, called makeslaveconf.pl, that automates the conversion. It's available in the tar file that complements this book; see the Preface for details.
3.8.4 See Also
Section 1.17 for instructions on configuring a name server as a slave for a zone.
BIND Name Server Configuration
BIND Name Server Operations
Delegation and Registration
Interoperability and Upgrading
Resolvers and Programming
Logging and Troubleshooting