I was recently downloading an old .wmv file format torrent with a few peers but no seeders.
As you can expect it took ages (about four weeks) to download entirely due to the absence of seeds (but I eventually struck lucky with some peers). I wondered if using two different torrent clients (uTorrent and BitComet) would help, and it came as a surprise to notice that the clients connected to the different peers - even though using the same torrent file, and the same tracker list. Maybe DHT comes into play?
Anyway, the question is this: I decided to run a file comparison check and it shows that there are ~1000 bytes (out of a total of 400 MB) that are different in the two versions of the file.
Both versions of the file work well and there is no noticeable difference in the result but the fact remains that is different file content.
The total file size is exactly the same on both files, and there is no one file with seemingly blank data. On both files there are occasions where one has a bunch of 0s while the other does not, but mostly it's different byte values altogether, e.g. byte #17 <-> byte #253
How can this happen? Aren't the clients supposed to check that the downloaded segments are correct?