DR per round or per Hit?

[Izod]

This question came up in a recent game and we have assumed that like elemental restance that is is per round but I was unable to find that paticular rule.

 

[KarinsDad]

Per hit.

Further clarification: Top of page 74 DMG.

"meaning the werewolf ignores the first 15 points of damage from every normal attack..."

There are a few places were it talks generically about ignores blows, so it is not always clear. But, here is one place that it is clear.

 

[orbitalfreak]

edit: beat me to it.

 

[Someone]