Hi Frank, As long as your certification (NCDA) hasn’t expired, you can take the NS0-504 or the 510, then you will be current and the new expiration for the NCDA will now be married to or match/align with the expiration of the 504 or 510. In other words, either NCIE exam will do, but they are not related to the updating of each other. Hope this helps. Best Regards, Ivel