Let’s say you are the owner of a small local cafe and there is this annoying customer named Bob who comes every day, order a dollar coffee and stays forever. Not so annoying? How about this then, Bob sits there forever and downloads big files from the internet(using your “free WiFi”) and consumes a big part of your network traffic. Some customers complain about your internet speed, some others just leave your cafe and won’t come back because your internet is too slow for them. Now Bob’s become annoying, right?
So you have decided to block Bob’s laptop from accessing your WiFi network instead of reason with him. You somehow have found out this customer’s MAC address(
like, “Alexa, what is Bob’s MAC address?) and added to your router setting
Figure 1 : The Bob’s MAC address is 64:80:99:8A:E6:25 and now he is banned from your network
On Bob’s screen, nothing will be shown. No warning message but just simply got him off the network. As Bob tries few times he realizes the MAC address of this laptop(which is 64:80:99:8A:E6:25) has been blocked. So he downloads a MAC address changer tool(here, https://technitium.com/tmac/ ) and changes his MAC address to go around the restriction you have set.
Figure 2. Bob’s MAC address changes
Although this does not permanently change Bob’s physical MAC address, now Bob can attempt making a connection to the network again and it’d go through this time.