Hi lately I was reading about IP addresses, how it is assigned to a system(using DHCP) n how they communicate in a LAN(via ARP), but i am not able to understand how Router is managing to send a packet frame to a particular address when there are billion of ip's are there.
Then I figured out that Router do not stores all the IPs rather they have frequently used IPs as dynamic IP n a default IP(
When a request come for unknown address it is transfered to default Ip,But again a next hop can also be not directly connected to destination so again it will send to
So my question is How this continous loop is finally broken and how router narrows it down to a particular server or device??

Thanks in advance

1 Answer 1


You may have already learned that network addresses (routes) can be summarized. That is, many network addresses can be summarized (represented) by a single network address (i.e a route). A default route can be considered a summary route that contains all network addresses. Because routes can be summarized, routers may not have complete information about the entire internet, but they may have a route to a large summary network that contains the destination. That is, they know enough to forward the packet to another router that will have more information.

So if you send me data, your provider may not know where my IP address is located. But it may know that my IP is in the range of addresses that are located in the United States. So all your ISP needs to know is how to forward it to a router closer to the US. That router will have more information to get the packet closer to me. It in turn will forward to another router with more specific information, until the data gets to me.

The Tier 1 and Tier 2 providers that make up the backbone of the Internet have routers that carry routes to all the networks connected to the Internet (currently more than 500,000 routes). Your IP packet will eventually be forwarded to a router that does know to get to the destination network.

  • Thanks for ur explanation. From ur ans i got another que are range of addresses is decided according to geographical location? Mar 18, 2015 at 18:37
  • you can look at this question: networkengineering.stackexchange.com/questions/17178/…
    – Ron Trunk
    Mar 18, 2015 at 19:26
  • RIR is the next to IANA. But its like a high level answer. Do they divided network address(Range-Specific),like if request comes for any ip between to it should be diverted to USA for example.Is this approach is being followed Mar 18, 2015 at 19:32

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