Users of a domain,LAN & of a machine PLEASE HELP ! IMP

Question

Hi...

How can we get a list of users of a company ??

Eg -
Assume that a person is working in IBM.

Now, IBM is everywhere - India, UK, US, etc and world wide.

Hint -All machines (Computers, laptops, etc) of IBM are connected to IBM domain.

Problem - How to get a list of all the users of IBM in asp.net in datatable and display them in a gridview ??

I have 2 things -
1. Domain - IBM.com
2. Global IP Address - 1.1.1.1
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How to get a list of IP Address and Computers Names of all the machines (Computers) connected to a LAN.
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How to get list of users of Windows OS ??

Eg -

In a machine where Windows 7 or Windows 8 is installed and I create 6 users in it,
how do I get the details of these 6 users of my machine in a datatable??

Please Help.