How ARP works : Basics

Step 1 : Source machine checks whether it has mac address of corresponding IP address, if not found it goes to next steps

Step 2 : The Source device will generate an ARP request broadcast message which contains following data

Src : IP address

Src : MAC address

Dest : IP address

Ste p 3 : All the devices which receive the ARP request message will process the packet. Apart from the original device (i.e who's IP is given in ARP request message ) all others will drop the packet.

Step 4 : Destination device will now update its own ARP cache and generate a reply packet towards Source device . This reply packets contain its own IP and mac address. It is important to note that this reply is unicast only.

Step 5 : Once the reply packet is received Source device will process the packet and updates its own ARP table based on the reply packet info.