If Frost receives ALL_DATA_NOT_FOUND, it keeps retrying this index during next board updates. But the current DoS attack uses many ADNF, and together with the backload (days to download backward) it takes ages until a board completes to update.
My question is: what is a good way to re-request keys that got an ADNF? Try it exactly X times, or keep it trying if we request keys for today, but don't try them again if we download messages for previous days, or what? I know, in theory those keys could finally arrive after weeks, so what logic should we use? bback.
