ADDRESS RESOLUTION PROTOCOL:-
Address resolution protocol determines the "mac address" of host when ip address of source and destination are known.the term "resolution" refers to finding address over a computer network,and the term address refers to the physical address or mac address,as the actual communication takes place via physical address.
Let us take an example two computer PC-1(source),PC-2(destination) are connected via ethernet having ip address are 10.12.2.73 and 10.12.2.1 and PC-1 has a mac address of 12:6e:eb:de:b6:ed. now in order to communicate between PC-1 and PC-2,we need to know about the mac address of PC-2. this is done by "ADDRESS RESOLUTION PROTOCOL".
Incase of ARPA at first "encapsulation" occurs that means the packet entered in the ethernet frame where we have to mention the source and destination mac address.but the PC-1 did not know the destination mac address,then PC-1 will sent a "ARPA" request to PC-2.its a broadcasting request that means all the host connect to the source will get the "ARPA"request.when PC -2 gets the "ARPA" request it will do two things:-
1.gives "ARPA"reply
2.it will also enlist the mac address of the source(PC-1)in the "ARP"table.
when PC-1 gets the "ARP" reply it will also updated its "ARPA" table with the destination mac address which is the main utility of the protocol.
There are 4 types of "ARP" messages that may be send by "ARP" protocol.
1.ARP request
2.ARP reply
3.RARP request
4.RARP reply
SUMMARY:-
in this way the "ARP" protocol works.
