How are IP addresses determined?

[Cityscape]

I always thought each computer had its own IP address, but I have 2 desktops using the same internet from a wireless router and both have the same IP address. I'm confused  . What determines which IP address a computer gets (internet, harware etc)?

[Geek-9pm]

Simple answer. Global and local.

Metaphor.William lives at 123 State street.Bill lives at 123 State St. Same person? No, William is in Las Vegas and Bill is in Chicago.

OK, not a very good metaphor.

The IP address thing was never meant to be easy to understand by humans. It is a fixed-length identifier that is used fro both for global and Local identification by  electronic switches. Read this:

http://www.computerhope.com/jargon/i/ip.htm

So you can expect your PC to enjoy two IPs given to it. You should also understand the the internet IP may not, by itself, fully identify your PC.

If two PCs need to connect directly to each other over the internet, some additional software or hardware is needed to do the job.

This is a very simplified explanation. For more, go to Amazon or you favorite book store and buy a thick book that explains the whole Internet Protocol mystery.

[Azzaboi]

Your router will be given it's own IP address (for example 192.168.0.1) the other computer(s) will connect to, this is known as the default gateway. It will also have a subnet class (normally 255.255.255.0).

Each computer has it's own unique IP either generated off that (for example 192.168.0.102, 192.168.0.103, etc) or are manually added. If these aren't different you will have issues when both computers connect at the same time. The same subnet class is needed to join the network.

IP Classes / Default Subnet Mask:

Class A: 1.0.0.0 to 127.255.255.255  / 255.0.0.0  
Class B: 128.0.0.0 to 191.255.255.255 /  255.255.0.0
Class C: 192.0.0.0 to 223.255.255.255 / 255.255.255.0
Class D: 224.0.0.0 to 239.255.255.255  
Class E: 240.0.0.0 to 255.255.255.255

Out of the five classes, the first three, A, B and C are used on the Internet by its users in order to communicate, while the rest, D and E, are reserved for other reasons. In most cases, you will always be working with Classes A to C. Class C is default for most routers.

The Router connects to the internet and gets it's own unique IP address for online access. Internet sites such as whatismyipaddress.com can automatically detect my IP address when accessed through the Web browser.

On a home network you may not find that computer's IP address but the address of a network router instead.

An IP address is a unique number that every computer connected to the internet is assigned.

[Computer_Commando]

I always thought each computer had its own IP address, but I have 2 desktops using the same internet from a wireless router and both have the same IP address. I'm confused  . What determines which IP address a computer gets (internet, harware etc)?

Unless you mean your Public IP, which is shown in my signature.  BTW, anyone who views my sig, sees their own Public IP.  I cannot see yours or anyone elses.  This website (and others) log your Public IP.

[Allan]

He's talking about local IP addresses assigned by the router.

[Computer_Commando]

He's talking about local IP addresses assigned by the router.

I'm not so sure, he says they both have the same address.

[jkolak]

Unless you mean your Public IP, which is shown in my signature. 

Curious. The sig also says I am using XP and IE6 both when using Win7 with Chrome and when using my Android phone.

[Allan]

Correct - I'm guessing except for the last number though

[soybean]

Curious. The sig also says I am using XP and IE6 both when using Win7 with Chrome and when using my Android phone.

I think the site he uses for that little trick hasn't figured out how to recognize Win 7 yet.  When I'm on Win 7 RC, it just shows "Windows" and the browser (which is shown correctly as IE 8 or Firefox).

[Cityscape]

Unless you mean your Public IP, which is shown in my signature.  BTW, anyone who views my sig, sees their own Public IP.  I cannot see yours or anyone elses.  This website (and others) log your Public IP.

I there some kind of difference between a public IP and other IP addresses?

Like Gmail for example tells me I'm using it at IP address 216.xx.xxx.39, if I use Gmail on my other computer (connected by a router) it will tell me I am using the same IP address.
ComputerHope also shows me that I am using the same IP address.

[jkolak]

The router provides one IP for the web and assigns individual internal IPs for the computers on the LAN.

[Computer_Commando]

1.  I there some kind of difference between a public IP and other IP addresses?

2.  Like Gmail for example tells me I'm using it at IP address 216.xx.xxx.39, if I use Gmail on my other computer (connected by a router) it will tell me I am using the same IP address.
ComputerHope also shows me that I am using the same IP address.

1.  Define "other IP addresses".  If you mean on you Local Area Network (LAN) or router, they all begin with 192.168,x.y.  The last number will be different for each computer.
2.  That's your Public IP.

[Computer_Commando]

The router provides one IP for the web and assigns individual internal IPs for the computers on the LAN.

The router does not provide an IP for the web.  Your ISP assigns it to your modem.

[greg]

Simple answer. Global and local.

Is it possible and is it good idea to hide your IP  with a proxy IP?

Some sites recognize that a proxy is being used and it seems to upset the adminstrator or Techs at the site.

What is your advice?

[kpac]

What is your advice?

Don't use proxies.