How to implement DNS server in a firewall.

[Penghui Wang]

Hello lists:

I have a domain name "example.com", it registered in a ISP.
And i could manage this domain and its subdomains on the website which
the ISP provided.

And i am in a lan, the intranet of our company. 
There is a dhcp server and a dns server one the host which is the
gateway of the intranet.

The domain name of the gateway is example.com.
If i want to resolve the example.com in intranet, it's impossible.

So i want to the dns server on the gateway to manage some part of the
domain name "example.com".

I have added the follow text in named.conf

zone "example.com" IN {
  type slave;
  file "pri/example.com.zone";
  master {210.34.0.14;}; // A public DNS server
 };

After that, i found that i could not resolve any domain names in
"example.com" except the entries of the dns server on the gateway.

I think i must  do something misconfiguration. 

The DNS server version is:
bind-9.2.5 

Thanks in advance.

Wang Penghui