How Does A Data Packet Reach The Right Destination
All this goes down to the addressing mechanism. For a system administrator, the actual destination address boils down to IP Address. A lot of hustle is going on beneath the network layer. Now we are talking of the data link layer and the physical layer.
Consider this is analogous to the postal system of transporting things. If a parcel is arriving from the other side of the globe, it must reach to the right country first. Then to the right state, city and then to the right street address. A similar thing happens when an Ethernet frame encapsulating the data packet is transported from the other side of the globe.
The frame first reaches to the zonal ISP of the country. The address of the zonal ISP is encoded in the destination MAC address. After reaching the zonal ISP, the frame is routed to the regional ISP. From there it is sent to the LAN, then the LAN uses the IP address encapsulated in the Ethernet frame to route the packet to the right system connected in that LAN.