Ccna routing and Switching Complete Study Guide

Start Frame Delimiter (SFD)/Synch    The preamble is seven octets and the SFD is one octet 

(synch). The SFD is 10101011, where the last pair of 1s allows the receiver to come into the alter-

nating 1,0 pattern somewhere in the middle and still sync up to detect the beginning of the data.

Destination Address (DA)    This transmits a 48-bit value using the least significant bit 

(LSB) first. The DA is used by receiving stations to determine whether an incoming packet 

is addressed to a particular node. The destination address can be an individual address or a 

broadcast or multicast MAC address. Remember that a broadcast is all 1s—all Fs in hex—

and is sent to all devices. A multicast is sent only to a similar subset of nodes on a network.