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Resetting a router can cause it to revert to its default. If you'd been using a static IP it may revert to dyanmic configuration, but is that theft?

I'm using DSL and I have a router, and I have a static IP. So one day I restarted my router manually by pressing a button on the back. Now my IP address has changed. I told my friend I had done this and he says I've made a huge mistake. He says I'm essentially stealing another person's IP address on the ISP. Is it true that I am committing a crime by changing my IP address by simply restarting my router?

No, you're not.

What your friend fails to realize is something very fundamental to how IP addresses work.

You don't take an IP address; an IP address is given to you.

Static IP addresses are assigned by your ISP. Typically, it's something you need to pre-arrange as part of setting up your account. The ISP determines what IP address to assign to you, tells you what that IP address is, and then configures their equipment to make sure that all data sent to that IP address is sent down the correct wires to reach you.

For your part, when you are assigned an IP address you then need to manually configure that in whatever equipment is connected directly to your ISP provided internet connection. Typically, that's your router. I have a static IP address, for example, and I had to go into my router and configure it use that address.

"You don't take an IP address; an IP address is given to you."

Dynamic IP addresses are also assigned by your ISP, but in a completely different manner. When you connect your computer or router to the internet, the software asks via a protocol known as DHCP (Dynamic Host Configuration Protocol) for an IP address. In essence, on being connected to the net the device sends out a broadcast: "is there anyone out there who can assign me an IP address?". The ISP's equipment responds with "sure, here you go, you can be x.x.x.x".

On your side, you enable all this automatic IP assignment by, once again, configuring the device connected to the internet properly. On a router or on a computer you configure the network connection to ask for a IP address automatically.

Two of the bigger differences between static and dynamic IP addresses include:

  • A static IP address does not change, whereas a dynamic IP address can. Each time a device asks for an IP address the answer could be different, and dynamic IP addresses are typically also only valid for some period of time, after which the device is required to ask again.

  • A static IP address typically requires manual requests and coordination with the ISP or issuing authority. A dynamic IP address is assigned automatically when your computer connects.

But in all cases, static or dynamic, the IP address was given to you by the ISP. You didn't take it. You can't "steal" what you were given.

Either of two things happened:

1) You actually didn't have a static IP address to begin with. Since you didn't mention configuring the router for it, I have to assume that this is at least a possibility. Hence, resetting your router didn't really change anything.

2) You did have a static IP address, but the reset on your router restored it to default configuration, which is almost always to ask for a dynamic IP address. Obviously, your ISP doesn't care, as they assigned a dynamic IP address and you were up and running. To complete your configuration, though, you'll want to go back into your router and configure it with the static IP address information you should have gotten from your ISP in the first place.

Article C3520 - October 3, 2008 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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6 Comments
andrew
October 3, 2008 3:05 PM

i started reading further on static ips, and ive found out that i dont have one. im using a DHCP. thanks a lot for clearing this up for me

Julian
November 2, 2008 4:35 PM

Also, when you manually configure your ip address to a DCE/DTE piece of equipment, you will need to assign a subnet mask i.e. 255.255.0.0 or 255.255.255.0. All this does is tell your equipment how many ip addresses it will enable.

Julian
November 2, 2008 4:43 PM

Oh, this only pertains to running your own private network. If you are running internet access through your router from a internet provider, an ip and subnet mask will automatically be assigned to your equipment based off your router's mac address (NIC card). All you have to do is make sure that your computer is set to " automatically obtain ip". And not in configure ip manually mode.

IAN
November 29, 2008 11:53 PM

I have known of people obtain some one elses IP and manually put it into there router settings.Can you stop this from happening?

ashish
February 17, 2013 9:45 PM

hello sir
while testing my internet speed on speedtest.net it showed me my ip address117.243.195.96 can i change this ip to117.205.103.64
please help me.

Mark J
February 17, 2013 11:41 PM

@Ashish
Your IP number is set by your ISP so there is no way you can change it. If your ISP owns the IP number you wish to have, you can contact them and request it, but this is probably unlikely.

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