My network is subscribed to a 16 Mbps cap. So if I download a file from let's say Facebook, does the ISP download the file from Facebook at a different speed then sends it to my network at 16 Mbps? Or does the ISP download the file from Facebook at 16 Mbps then sends it to my network at the same speed? A simple diagram that could express my confusion:
my network <-- 16 Mbps transfer -- ISP <-- ??? -- Facebook
As for upload, I'm also confused as to which part of the networking process the limit is enforced.