Ethernet Frame

Preamble- Preamble is of 8 bytes. It contains bit pattern 10101010, and is used by the receiver to allow it to establish bit synchronization (there is no clocking information on the ether when nothing is being sent)

Start frame delimiter- is a single byte, 10101011, which is a frame flag, indicating the start of a frame.

Destination Mac Address- When a message is sent between host on a network or the same switch, the switch check its mac address table for the destination address. A switch mac address table contains a list of all active ports, host or PCs mac addresses that are attached to it. If the destination Mac address is not found in the table, the switch will not have the necessary information to forward the message. When the switch cannot determine where the destination host is located, it will flood or forward the message out to all attached host. Each host compares the destination mac address in the message to its own mac address, but only the host with the correct destination address processes the message and responds.