In standard online Texas Hold em, an Ace serves as both the bottom or top of a straight, e.g. A-2-3-4-5 or 10-J-Q-K-A.
My dumb question is; can the Ace be both high and low, e.g. is K-A-2-3-4 a legal straight?
No, that’s not legal. My friends and I call that “wrapping around” and gives you nothing better than an Ace high hand.
It’s legal in certain rummy games, where it’s called “going round the clock.” Not legal in poker, though.
I’ve heard that it’s legal in certain variants of poker or as a relatively obscure ‘house rule.’ (Just about anything is legal as a house rule, if all players agree to it beforehand.)
Not common at all though. Similarly, it can be decided that aces cannot go low in straight, only high.
When going into a game which you think might have sligtly different house rules - ASK. You would hate to be betting that the wrap around is not valid and find that it is beat out your two pairs you just bet the farm on.