IP addresses

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um. i would just like to say that i use kali, and that every time i connect the IP address show up, but its always different. why is that, i thought IP addresses were supposed to stay the same?

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Aside from the static and dynamic posted about previously byrb300+ (good post too) there are also rollovers. When you connect to busy sites they are often using multiple servers to handle the traffic. DNS's can be set up to use different types of access to these multiple servers so that on DNS entry can be used for many servers. The easiest, and most common, is the roll over. If you have three servers where Server1 has IP1 etc. Then the first time your DNS name (URL) is resolved by your DNS it will return IP1, the second time IP2, third time IP3, fourth time IP1 again, and so on. This spreads out the load without requiring a ton of URL's. There are also load balancing algorithms that work similarly but are more efficient where the servers are actually polled for availability.

One excellent example you can see this with is Yahoo. If you resolve yahoo's DNS name a number of times you will get different servers almost every time. There is just no way one server could handle the sizeable load a site like Google or Yahoo have to deal with. BTW for this type of setup the servers used to be required to have static IP's. When I set up this type of system I had to fat finger in the IP addresses. Newer DNS's may allow more dynamics but I seriously doubt it for this type of implementation.

I would like to have some idea , if you guys have time to listen .I'm sure this has been written somewhere else - or you might know it already .
IP : Public and Privite
Private : Define clearly in RFC 1918 : 10.0.0.0->10.255.255.255 , 127.0.0.0->127.0.0.255 , 172.16.0.0->172.16.255.255 ,192.168.0.0->192.168.255.255 . These IP don't have to obey the class rule . Which mean 10.0.0.0/24 or 192.168.0.0/16 is a valid one .
Public : All the rest IP , and below 224 which is considered class D.

When you use Dial-up service , (ISDN or PSTN) , you connect to the Internet via your ISP which will provide you an Public IP (depend on Geographic location - My VietNam is 203.162.x.x) from the IP pool which the ISP are given itself by a larger IP-leaseable ISP. So , when you are using such Circuit-switch connect , and when the line are dead , you do not have any Public IP . Using a NEO Monitor IP , i can capture my ip (or simply ipconfig command) and the Public IP of other one that i have a TCP connection with .

Now about the leased ip stuff . Rarely someone at home rent a whole IP or an IP network . Small company who want to provide internet or VPN to a number of users can rent at least 4 , 5 IP ( 1 for WEB server..ect..) . And the inside network could use IP private which is unlimited and when a user need to connect to internet , it's obvious that he/she needs a public one . So Router , or Server with Nat/Pat feature can translate such private IP to public IP , and vice versa when a unknown Internet host want to access your Web server which has local IP .

However , large company buy an range of IPs and allocate each host with an public IP . In such situation , well , the host is more vulnerable unless nessesary precaution must be taken .

Well , it is just something i know .

ok. thanks for the heads up. i knew there was a reason and i was pretty close to the answer :). thanks anyway, though

r3b00+: but if i have a leased line connection,that means i never get d/c then my ip wount change, is that right ?

Bimmer: If youve a leased line you should have a static IP address, but im not too sure to be honest.
BUt if youre paying for a leased line, which isnt cheap then im nearly sure youre gonna have a fixed address.
Its easy to check yourself!

Someone else here might have a better idea.

Cheers

r3b00+

lol