I want to know how a large media or any file is sent from server through network and finally received at client. And want to improve the download functionalities. Need some articles or your idea's for support. I am lost because i am getting improper file. Please help me understanding what are things that i need to note.

Note : I was using file pointers and downloading set of bytes. Its worked to too slow. And how do i setup a low bandwidth network locally. so that i can exactly confirm