For some rolls in Pathfinder, such as attack rolls and saving throws, a natural 20 is an automatic success and a natural 1 is an automatic failure. The weakest character always has a 5% chance of success and the strongest character always has a 5% chance of failure.
For some other rolls, such as skill checks and initiative, there is no automatic success or failure. For skills, if the DC for a thing is greater than 20 plus your modifiers, then you simply can't do the thing. A level one commoner with a 3 dex and no ranks in acrobatics can't jump over the moon or leap across the ocean no matter what he rolls.
What about caster level checks, concentration checks, or rolls to overcome spell resistance? My gut tells me that automatic success failure should apply to those rolls, but I couldn't find the rule. Is there a rule somewhere that I've missed?
If the DC is greater than caster level + any applicable modifiers + 20, then is the caster simply incapable of doing whatever they're trying to do, or would rolling a natural 20 allow them to succeed anyway?
Also, if you think of any other d20 rolls that I haven't mentioned, is natural 20/natural 1 automatic success/failure for those rolls?