I assume you'll be flying IB
all the way? In that case you should have no problem, as they'll give you your boarding pass at DUB
and your bags should be checked all the way to MEX
. I don't know how much time you have between flights but, say, 90 min, would be plenty of time (considering the fact that you wil not have to go through security at MAD
and that, since you're connecting from a non-Schengen country to a north-american destination, you will not have to go through passport control at MAD
You're lucky you won't have to go from the domestic terminal to the internationalterminal (that's an awfully long walk).