As soon as Littlepay has received a declined response code from the customers issuing bank, the card is immediately added to the deny list. The same happens for transactions we have been able to authorise through debt recovery, as soon as we receive the approval to authorise the transaction, the card is then removed from the deny list.
The ticket machine will be able to download the most recent deny list at any time during the day, but this is usually set to a specified period of time throughout the day. We would normally see requests coming into Littlepay to download the deny list every 15 minutes but this time limit will be configurable with the device vendor.
The data being downloaded is very small but will always require a strong internet connection in order to be able to download the most recent information, in order to have the most up to date list on the ticket machine.