dns make the network slow

[gliu]

Hi

My leader designed a network in which the dns server is response for solving the internet host name and internal  host name as well.
Now I set up the dns server ,of cause there are two zone ,one for the outside one for the inside like this.

     internet
            |  (1.5M T1)
  --------------------------210.233.49.0
  |          |          |

 DNS   HostA  HostB
  |          |          |
----------------------------192.168.3.0
           |

      internal  192.168.2.0

But I found it is very slow to access the HostA and HostB using "ssh" from internal,which will cost 1min.(I use the ip but it is also slow,so I think it tries to resolve the name from the ip).After I login in the Hosts eg HostA,I can ping HostB and ping yahoo.com by name very quickly.

But it is impossible to send out email(qmail) even between HostA and HostB.And I found it is very slow  if I use " netstat -l" in all the hosts including the DNS server.

I guess the dns tries do query the ip first from the "root.cache" file and then I delete all the records in the file.It becomes very fast.(mail ,netstat -l and ssh)

My problem is I must use the root.cache to solve the internet server.(I downloaded the newest  "root.cache" file and put the nearest server at the head of the file.)I guess one DNS server is not able to solving the internet and internal host name as the chart shows.I must use 2 seperated DNS servers.

Am I right? If someone met the same problem before or knows how? Would you please help me?

By the way ,there is no error in the /var/log/messages when I start the named.

Thank you very much.