1. ARP is a stateless protocol(a stateless protocol is a communications protocol that treats each request

as an independent transaction that is unrelated to any previous request so that the communication consists

of independent pairs of request and response). Network hosts will automatically cache any ARP replies they

receive, regardless of whether or not they requested them. Even ARP entries which have not yet expired will

be overwritten when a new ARP reply packet is received.

　　2. The communication between 2(or more) hosts in the same LAN did not need the Router to forward the

package.