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DAVIS: So, before we communicate on a network, we must resolve the IP address
into a MAC address, and for that we use what's
called address resolution protocol or ARP for short.
What will happen is the source computer, or the source device
will send out an ARP message
and that message may say
"Who has one nine two dot
one six eight dot zero dot one? Please tell
one nine two dot one six eight dot zero
dot two." This message happens to be what's called
a broadcast.
And a broadcast message is a message that is
received by all computers on a network
All devices on a network receive this broadcast message. So every
computer will look at their IP address and say "Oh, do I
have one nine two dot one six eight dot zero dot one? Is that me?"
and if it's not, then all the rest of the computers that are not
one nine two dot one six eight dot zero dot one will discard that frame
discard the ARP message. Won't even reply to it, just drop it.
but the one computer that does have one nine two dot one six eight dot zero
dot one will say "Oh, that's me" and it will construct what's
called an ARP reply and in the ARP reply it says
"I am one nine two dot one six eight dot zero dot one
and my MAC address is D eight D 1
CB etcetera. This way, the source computer
can construct an ethernet frame with a source MAC address
and a destination MAC address which is what is required for communicating on local area
networks
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