What?!? Corking is how you know they're good and hot. As they mature, you cut that water back and give them long dry phases to up the heat. Makes them even more delicious!
The black is fine, I think. Usually blossom end rot or other bad stuff looks kinda swollen and yellow/tan colored, in my experience. Black usually means they're ripening. It looks black now, but it's actually red and green pigments at the same time. As the ripening progresses, the chlorophyll goes away leaving red chilis.
The corking thing was just a bad joke reacting to the comment above. But these are cayenne peppers not jalapenos so still, no corking should be happening. Same thing regarding changing color to black while ripening. I know that's the case with jalapenos but I'm pretty sure that's not happening in my case.
There's a chance it's a little sun scald, but this looks more like ripening to me. Especially since the bands go all the way around, and aren't just spots on one side.