When our router get damage from branch end then how to take back up from our end?

Q1: Describe the specification and characteristics and applications of a modem. Q2: Differentiate between broadband and baseband communication.Q3: (i) Explain through a diagram how does ATM network work?(ii)Discuss the ATM cell format.Q4:(i)List and describe all the layers of TCP/IP with the protocol functionalities and standards.(ii)Make a comparison between Switches and Hubs.