Is Exhibit A from an Ultrapeer?
A. It’s possible– but it could be from either a leaf or an Ultrapeer. Given that the network is made up mostly of leaves (about 10% are Ultrapeers), chances are it’s a leaf. Ultrapeers indeed act somewhat like card catalogues, with leaves uploading their hash tables to the Ultrapeer. The “card catalogue” analogy needs a bit of fine-tuning though, because all the Ultrapeer knows about their leaves’ files are weak hashes of the _file names_. This is very different than hashes of the file content (which is what could uniquely identify the file). The Ultrapeer’s card catalogue is what in tech terms is called a “bloom filter” — this is a piece of data designed to take lots and lots of information and make itsmaller and easier to deal with. As an example, suppose the filenames Alice, Bob, Cory and David might all hash to the number ‘1’. The filenames Edgar, Frey, George, and Harry might hash to the number ‘2’. When the Ultrapeer gets a query from someone else on the network, it will determ
