Most of the time a primary DNS will suffice and this is usually provided automatically to computers with that option enabled. But if you are forced to input a DNS server all you need to do is go to a computer on your network and open a command prompt and type "ipconfig /all" without the quotes and you should have all the info you need.
i have a playstation portable. i have everything i need for internet connection, but i cant find out my secondary dns. i dont know where to find it, but as soon as i do, i'm set. please help me! anyone!