sounds a silly question I know but whats to stop me say giving my own webserver a public ip of oh 184.108.40.206? I know there would be another system somewhere with that address etc. and it shoudnt be done but what actually stops me from doing this?
I know you have to be assigned an ip from an isp etc and that private ip addresses are not accepted by routers. how does "the internet" keep only officially assigned ip's in use.
Internet routers have what you call "routing tables". Every block of IPs is programmed into these tables. You can force your machine to have 220.127.116.11, but if the internet routers don't have your entry, your IP will never work.
To put it in non-technical terms… for the same reasons you can’t decide one day you no longer live at "123 Conformist Lane", but instead "456 Contrarian Rd". You don't control the directory/mapping. You can't self-assign an IP address anymore than you can self-assign your home address. No one will find you because everyone else's directories/maps contain the directions to “123 Conformist Lane”, no matter what you decide to hang on your front door. You, like me and most everyone else, are at the bottom of the Internet food-chain, and simply told what is and isn’t available for public IP addressing by our Internet superiors (the most immediate being the ISP).
I see, so the IANA allocates blocks of ip addresses to the isp which means they basically tell the isp you are allowed to use oh 18.104.22.168 to 22.214.171.124 then if i order an ip address of the isp they tell me you are allowed to use 126.96.36.199 so then i punch that into my tcp/ip properties for my eg. public web server and perhaps the put an entry into their routing table?
If some one from a remote computer tries to access my site they can connect because the ip address is valid. I understand the function of the routing table so.. uh
perhaps if had visualise the path from the user sending the web page request to its arrival.
bob sends http request for a web page on my machine. request It goes to bob's isp and bob's isp's big ass router which looks up its routing table to find out how to get to my ip and they are somehow pointed to my isp's routers and my isp maintain's the correct routing tables needed to find my ip/web server.