A multilayer switch (MLS) is a computer networking device that switches on OSI layer 2 like an ordinary network switch and provides extra functions on higher OSI layers.
The major difference between the packet switching operation of a router and that of a Layer 3 switch is the physical implementation. In general-purpose routers, packet switching takes place using software that runs on a microprocessor, whereas a Layer 3 switch performs this using dedicated application-specific integrated circuit (ASIC) hardware.

Address Resolution Protocol (ARP) is a protocol for mapping an Internet Protocol address (IP address) to a physical machine address (MAC address) that is recognized in the local network.

Explanation/Reference:
HTTPS, which stands for Hypertext Transfer Protocol Secure, makes it more difficult for hackers, the NSA, and others to track users. The protocol makes sure the data isn't being transmitted in plain-text format, which is much easier to eavesdrop on.