Suppose you want to access any website like google com. The browser behind the scene will use the application layer services such as HTTP for establishing the connection between two systems. Now, the HTTP will get help from the transport layer including TCP (Transmission Control Protocol) and add the information like Port number and the details regarding transport layer protocol. Now, the network layer will add IP information. Network Layer will add the source IP address and the destination IP address. How will the source computer know about the destination IP address? The DNS will resolve the URL or name to the IP address. Now, this data packet is handed down to layer 2 i.e. data link layer. In layer 2, the communication happens mostly over the MAC address or physical address(MAC address is the permanent physical address of the computer). So how in the world would the source computer know the destination IP address or the MAC address associated with it? This is where ARP comes into the picture. ARP helps in knowing the MAC address of the destination given the IP address. So, let’s dive deep into ARP and start the blog.
Address Resolution Protocol is one of the most important protocols of the network layer in the OSI model which helps in finding the MAC(Media Access Control) address given the IP address of the system i.e. the main duty of the ARP is to convert the 32-bit IP address(for IPv4) to 48-bit address i.e. the MAC address.