@hui, sure it works this way ONLY if you download entire directory. If you download "current" ISO at least I would expect that the associated sum would be for current was well (this is especially true because "Snapshot" ISO has its own sum file). There is no indication the current and snapshots are related (what's more DVD current for example is 4.4 GB, and snapshot is 4.3 GB, at least as they are listed at the web page).