Think it through · Start with a story
A girl asks a robot: “Do computers find a neighbor’s computer and a faraway server in exactly the same way?” First, check whether the destination is on the local network.
Break down the process
- Read the destination IPKnow where data is headed
- Reachable locallyUse the local link
- Remote networkSend it to a gateway
- Move hop by hopContinue to the destination network
Devices use addresses, prefixes, and routing information to decide how to send data.
On a local network, a device needs to find the right link-layer destination. To reach another network, it usually sends data to a gateway first, and routers forward it from there.
It is like delivering a letter within the same building versus mailing one to another city: the first delivery step is different.
Your turn to try
When visiting a faraway website, does your computer need a complete map of every router in the world?
Have you decided? Open to see the explanation
No. It usually follows local routing rules to send data to the next hop, and later devices handle the next steps.
Take away one discovery
Devices use addresses, prefixes, and routing information to decide how to send data.
Try covering the diagram and explaining each step to someone at home. If one step is unclear, go back and look at that card again.