You might be thinking of incremental backups which also saves space but is not the same thing.
If you for example ran deduplication on a file server and a bunch of users uploaded the same files in multiple different directories, deduplication would remove all duplicate copies and just link them together. This has nothing to do with snapshots. btrfs might support deduplication but now this software does too. Your comment was completely unnecessary since not everything in the world can or should run btrfs
Not sure you would even need encryption. Surely It can’t be illegal to ask the root servers (and all the other DNS servers involved, because the root servers only have IPs for TLD DNS servers) for IPs
Sure but maybe they don’t want to use btrfs. Ever thought about that?