Question: Why should BroadBand Internet Connection to be connected through LAN? 

Answer: LAN means Local Area Network.  It is the cables, or wireless system that is IN your home.  The content however comes through 2-wire telephone line (DSL) or Cable.\n\nSo you do not need LAN to receive the BroadBand connection. But you need LAN to connect the router to your computer or share connection with different computers.
This question from the Yahoo Q&A forum is categorized in the topic: Health