please help me.
need answers any body can help......?
what is domain controller ?
why we need domain controller?
Role of Domain controller in windows server 2008 ?
Key Features of Domain Controller?
Architecture of Domain controller?

why I do not listen to the domain controller.

These are a lot of questions to answer in a single response.

A domain controller is a server role that is responsible for authentication and authorizatoin services in a domain. What is a domain? A domain is a centralized system that stores the security principles for your network resources (user, computer, group accounts, etc..).

A domain controller is generally implemented once you have 10 or more computers on the network, where a simple workgroup is too difficult to manage with repect to securing your accounts, resources, services, etc..

I have several dozen articles that cover Windows Server 2008 roles including DC, DNS, DHCP, etc... Feel free to take a look and come back with questions.

I would recommend that you create a thread for each specific question. It will be too difficult to maintain a thread with more than one question.

Or, you could do a lot more to research these questions yourself. Having these points written in your own words would impress the teacher marking your homework no end. :)