For example, www.yahoo.com resolves to eight different IPs. If I set the number of threads to 8, would it open all threads on the same IP, open one thread per IP, or something in the middle (random?)
Thank you for writing us.
Mass Downloader will open all threads to the same IP. It asks Windows to resolve the domain name once (on the first connect) and use the returned IP.
We added it to the Mass Downloader development list.