Answer to Question #59806 in Programming & Computer Science for Olivier

Question

Why do we still need IP Address when we have MAC Address? How about port numbers?

Answer 1

MAC addresses and IP addresses operate on different layers of the internet protocol suite. MAC addresses are used to identify machines within the same broadcast network on layer 2, while IP addresses are used on layer 3 to identify machines throughout different networks.
Even if your computer has an IP address, it still needs a MAC address to find other machines on the same network (especially the router/gateway to the rest of the network/internet), since every layer is using underlying layers.
Port number is used to identify an application/services which you want to talk to on your system.