Armour question - Damage reduction

This is about dammage redution which apparently doesent stack...

My question is, if a piece of knights or ascalon armour which has dammage reduction is worn, will that dammage reduction apply to just that body part (i.e. chest or legs etc.) or will it be for all body parts?

Reason I'm asking, could I get 1 piece of the set to get the dammage reduction bonus for all my other pieces of a different set, or will i need to get all the pieces to benefit from the dammage reduction on all my body parts?


Thanks

There are many threads about this.

The damage reduction is global and do not stack. Most people do just buy one piece of Ascalon or Knights, and the rest say gladiators.