You want to add a new zone or delete an existing zone without restarting or reloading a name server.
Add a new zone statement to named.conf or delete an existing one, then run rndc reconfig (for BIND 9) or ndc reconfig (for BIND 8).
It's nice to avoid restarting a busy name server, since restarting clears the cache and takes time on a name server that is authoritative for many zones. A reload, while it doesn't clear the cache, can take time as the name server checks all of its zone data files to see if they've changed. Using reconfig avoids these issues, just scanning named.conf for added or deleted zones.
ndc supports reconfig as of BIND 8.2.2. At BIND 8.2.3, though, you can also use ndc reconfig -noexpired, which prevents the name server from trying to load expired zones.
5.7.4 See Also
"Controlling the Name Server" in Chapter 7 of DNS and BIND.
BIND Name Server Configuration
BIND Name Server Operations
Delegation and Registration
Interoperability and Upgrading
Resolvers and Programming
Logging and Troubleshooting