Hybrid of client-server and P2P Skype Internet telephony app Finding address of remote party:centralized server(s) Client-client connection is direct(not through server) Instant messaging Chatting between two users is P2P Presence detection/location centralized: User registers its IP address with central server when it comes online User contacts central server to find IP addresses of buddies 2:Application Layer 102: Application Layer 10 Hybrid of client-server and P2P Skype v Internet telephony app v Finding address of remote party: centralized server(s) v Client-client connection is direct (not through server) Instant messaging v Chatting between two users is P2P v Presence detection/location centralized: • User registers its IP address with central server when it comes online • User contacts central server to find IP addresses of buddies