[Macha]

I can't say I've noticed this, and I'm a little surprised DNS gets much use in bittorrent at all, is the client doing rDNS on peers or something?

[talideon]

Essentially, yes. It's basically looking up the PTR records. If you look at the UI, you'll see them listed in the peer list.

[MayeulC]

Probably just resolving tracker IPs.