Your card limit gets checked on every transaction. There doesn't seem to be a technical reason why information flow back to me should be limited in any way. If the extra layer fails to work the transaction fails to pass.
> Your card limit gets checked on every transaction.
Nope. The merchant can choose the level of verification - in some cases, like copying the card with an imprinter [1] or running phone transactions (yes, that is possible - it's called MOTO [2]), it's obviously impossible to check card limits.
Downside of CNP transactions is, the merchant is fully liable for anything from fraud over chargebacks to exceeding limits.
And then you got card-present transactions but the network connectivity is down for whatever reasons... been a while since I messed with that, but at least for German cards you could configure the terminal to store the account details for later submission when connectivity was restored.
I remember being charged after a while when paying for bus/metro tickets in some places, I think those machines process transactions by batches or something.
