question: how does a knows that SFO is the right place to send as Ethernet frame
subnet Mask:
its just anotherway of saying that the prefix length is the slash 24
这张图的意思:
if its not on 192.168.9.something… then send it to 192.168.9.1 router
我们知道了我们想发给SFO的IP地址 但是我们需要知道怎么到它的MAC地址
need a protocol that use to send a broadcast to everybody on ethernet network asking who own this IP address
Address Resolution Protocol(ARP):
broadcast addres : 255.255.255.255 ..1111 1111… (ff ff ff ff)
ethertype 0806是ARP协议
protocoltype 0800 是IP