Explain the following layer-2 (LAN) network concepts CSMA/CD in a scenario with 4 x PCs connected to a hub. (3 marks) Why does a full-duplex switch behave like a shared hub immediately after start-up? (2 marks) How does auto-negotiation function on a switch port and what are its advantages? (3 marks) What are the most prevelent weak points of hubs, and how is it overcome by switches, but to what detriment? Which kind of switch, suffers the least under this detriment? (2 marks)