To find all the alive IP addresses ( i.e all the IP addresses which are currently in the running condition ) , you should download a famous software known as CAIN AND ABLE.
DOWNLOAD IT HERE
After the downloading the above software, just follow the below instructions and you will have all the alive IP addresses along with their MAC addresses.
1. Install the software and open it. It looks as follows
2. Now, click on configure. Now a table will be opened and there select your network adapter and click ok.
3. Now on the top right corner click on the button start/stop sniffer button (this is very imp that this button should remain selected to sniff the IP addresses).
4. Now click on sniffer tab.
5. Now click on the '+' button. And again a table will be appeared.
5. Here choose All hosts in my subnet and click ok.
6. And thats it. Now all the alive IP addresses will be scanned and displayed on the screen. :)