Why might you want to perform a MAC Address Lookup?
There are many reasons why you might wish to perform a MAC address lookup. One common example is when a network administrator sees a mac address in the ARP cache of one of his her her switches and doesn't recognise it. Maybe it looks unlike any of the other MAC addresses on the network. Maybe this particular MAC address appears to be the source of some network problem.
In such cases, one would visit a MAC address lookup website in order to ascertain what type of device they are looking for.
For example, you have an unidentified device on your network that is running some port scans. You find it's IP address, look up the corresponding MAC address in the ARP cache or MAC table then do a MAC lookup online. Now you find out the MAC was issued by Apple so you are most likely looking for an iPhone, Ipad or MAC Book.
So what is a MAC address
MAC address stands for 'Media Access Control Address'. A MAC address is the unique identifier 'burnt in' to every ethernet network interface card (NIC). In fact, some vendors actuallt call it a 'burnt in address'. The MAC address lives at layer 2 of the OSI model. The MAC address is not routable so is only used to communicate with a single subnet or 'broadcast domain'. Should your data need to leave the local subnet, the layer 2 'frame' is packaged into a layer 3 'packet', complete with a source and destination IP address, and sent off to the default gateway.
You can rest assured, no remote entity will ever see your MAC address since, the source and destination MAC addresses are replaced at every hop of the route. The furthest you own MAC will ever get is to your router or firewall. This is why it is possible, and has been known for mistakes to be made, and NIC's to be issued with duplicate MAC addresses. Whilst a MAC address should be unique in the world, a duplicate would never be a problem, unless two identical MAC addresses found themselves on the same subnet or broadcast domain. Then they would be mayhem!
I hope you enjoyed my brief explanation of MAC addresses and I hope you enjoy using this site to help identify those rogue devices on your network!