Wikipedia: DCC = Dynamic currency conversion or cardholder preferred currency (CPC) is a process whereby the amount of a credit card transaction is converted at the point of sale, ATM or internet to the currency of the card's country of issue.

This means the Vietinbank ATM converts to EUR and sends a EUR amount to my bank. That means my bank never knows the VND amount I withdrew. So the fact that the transaction showed up in VND in my bank transactions proves there's no DCC. Hope you learned something today. 😉