Questions about some elementary concept

[Ellen Zhao]

Hi,
as a tyro to networking I am investigating my own box and local network. Dr. den Haan�s introduction to DNS is comprehensive and inviting but there�s still some issue I don�t quite understand:
1. Equipped with a router, my room mate shares an adsl Internet connection with me. Our ISP is 1&1, Germany. When DHCP enabled, the connection was very unstable, lost ping frequently. Then I disabled DHCP and IP routing, specified some static local IP address for both my room mate and me. I didn�t know the IP address of our DNS server, so that simply set the address as 192.168.1.254, the same as the default gateway. But, it works. And the connection is rather stable, but why? I don�t understand, my very humble 192.168.1.254 is not wielding any power any way.
2.Sometimes I use DameWare to invoke remote help. In order to open some port, I had to enable DHCP and dynamic routing again, why? Is there any alternative to open the port xxxx on my computer without enable DHCP?
3.What�s DMZ host?
4.How does Java address a port?
Thanks in advance.

Regards,
Ellen

[dhiraj dhiraj]

Hello ,
for the first question the solution is bascially all the computers behind the router are taking internal IP. This IP has nothing to do with actual IP. Your router has the actual IP which is seen by the world.