Connecting M17 R5 to Monitor

Hello,

I want to connect my M17 R5 to an external Monitor. Both my Alienware and the external Monitor can go up to  2560x1440. As I can see, I have a Mini Displayport. So I would need to buy Mini DisplayPort to Displayport for best results? (My Monitor does have Displayport. But when I look at the MiniDisplay to Display port from Dell, it says it can only go up until 2058 x 1600 Pixel. What is the best and easiest way for Gaming to connect it? Many thanks!