For example, if a router connects a LAN to the backbone of an ISP, the router knows the LAN's IP addresses. To know some information about routers outside the network it serves. If packets from inside the LAN are addressed to some unrecognized host, the router passes the packets along to an Internet router outside the LAN for continued transmission. Through decisions based on a number of routing protocols and current conditions, routers make decisions about which router they should send their outgoing packets to. Just as you learn from the daily traffic report which highways and streets to avoid, routers learn about disruptions and delays on network segments from other routers.
Routers store continuously updated information about route availability.
Route status can change based on traffic volumes, hardware malfunctions, and planned outages. Not every router on the Internet knows every available route. If a particular router does not have specific information about a requested route, it will pass the request to a router that has access to more information about how to get to the desired location. Looking at the addressing schemes that have been used in the past and the ones that are currently used gives us some insight into the important aspect of Internet routing called addressing. How a computer is identified determines how efficiently information can be delivered to it or accepted from it.