How do you know if monitor has a 1:1 ratio?

[Ghost9]

I've been looking through specs on LCD monitors but have not been able to discover any detail that describes this. How can you find out if a monitor keeps a 1:1 pixel ratio, or if it stretches and distorts?

 

[Hose]

"... it should be noted that the Nvidia video card drivers can force 1:1 mode.

Has it been your experience that this *always* works, or are there monitors upon which it doesn't?