TOPIC: DR vs Monster Ranged attacks question

I am trying to get right when player's Ranged DR applies to a monster's non-melee attack and when it does not. I was told this past run but didn't write it down before re-focusing on the adventure.

My Elf has 7 Ranged DR (4 Kvothe, 2 Shaed, 1 Saga). A monster hits me with a non-melee, non-Eldritch attack and I want to quickly know whether or not Ranged DR applies. Is the rule "It applies after the save?" "If you had to roll a saving throw then it doesn't apply?" "Other? The Magical Damage Resolution Flow Chart on Page 70 of the TD Player's Handbook implies the former but only talks about spells or magical damage, and I don't want to interrupt the combat to ask if the attack was a spell/magical.

Thank you very much.