详细的例子 DNS Sample BIND Configurations
http://www.zytrax.com/books/dns/ch6/
named.conf全部的参数 List of Statements
http://www.zytrax.com/books/dns/ch7/statements.html
HOWTO - Delegate a Sub-domain (a.k.a. subzone)
http://www.zytrax.com/books/dns/ch9/delegate.html