Networking - Data Link Layer Interview Questions

What is a MAC Address? - MAC (Media Access Control) addresses are globally unique addressed that are written into hardware at the time of manufacture.........
MAC vs. IP Addressing - Whereas MAC addressing works at the data link layer, IP addressing functions at the network layer (layer 3).........
Define Spanning-Tree Protocol (STP) - Spanning-Tree Protocol (STP) as defined in the IEEE 802.1D is a link management protocol that provides path redundancy........
What is VPN? - A VPN is a service that offers secure, reliable connectivity over a shared public network infrastructure such as the Internet..........