How to change (Dynamic) IP address in Windows 7 or Vista?

Thanks for taking the time to actually read what I already stated before just telling me what I already know Jim, appreciated.

My service is wireless broadband (Clear Wire), the modem does not act as a router and I'm not using any kind of router, nor does my system have any kind of local (196.xx.xx.xx) type IP.

Everything you said seems to be exactly in line with what I thought I already knew, probably the main reason this entire thing is bugging me so much. I would agree, the DHCP server, in this case my ISP service, is in control of assigning the IP address.

Just to help you out, I'm not a guru, but I have been using computers since Windows 3.11 was around, and come from the days when all network connections had to be configured manualy by the user, so I'm not coming from complete inexperience either. I've done all this a couple few times.

I've argued this point about the DHCP server assigning my IP with my ISP, I even had my complaint escalated to a higher level support. Their answer to me was their DHCP servers reassign new IP addresses every night around midnight. They also said my computer may be requesting a specific IP and if its available then it will allow this request.

This seems to be exactly what's happening. What's new to me in Vista and 7 is the computer deciding to make this request, and worse, not allowing me control over changing it. Like I said, I can plug in an XP laptop to this same modem, get a dynamic IP assigned to it, then at a prompt just run IPCONFIG /RELEASE followed by a /RENEW and instantly obtain a fresh IP. I can do that all day long with no problems, yet, as soon as I plug this once Vista (now 7) laptop in it doesn't work, even if I select to open the CMD prompt "As Administrator". It just hangs onto the same exact IP address.

Theory 2 that I also shot full of holes was maybe the DHCP server is recognizing the MAC address of my NIC card and always assigning the same IP to it. This can't be the case though, I tested this theory out and it doesn't work. Using an Ubuntu boot disk I booted the same Win7 computer into Linux, with the same exact MAC address on the NIC I am given a different IP, and can change it at will in Linux by releasing and renewing the IP assigned to me.

So, from what I do know, and have ruled out by trying, is some how, somewhere Vista and 7 seem to be storing assigned dynamic IP addresses and requesting this same IP from the DHCP server. My ISP's DHCP server must not get enough new requests to use up all its available IP's so even with the modem off for a week, when it comes back on line the same IP my computer seems to be requesting is still available and gets reassigned to me again.

If I reinstall Vista (tried this on another computer that needed a new hard drive installed), that information gets lost and a fresh IP is assigned after the Windows reinstall. Just to be certain, I even tried to force my assigned IP to be dumped and changed, couldn't be done, reinstalled Vista again just to see what would happen and it gave it a different IP.

So, what I'm trying to find out, for the sake of my own sanity, is where is Vista and 7 storing this information so I can go in and manually clear it. The registry value older versions of Windows used that I listed above is still there, yet clearing it there, or even editing a change there does not clear it, if I reboot the old IP turns right back up in there all over again.

To me, this is a significant privacy, and security concern/issue.

I have searched from one end of the web to the other looking for an answer to this, what I find are many answers telling people what I already know how to do, and what use to work perfectly under XP and prior versions of Windows. What I'm also finding are many other people now using Vista or 7 who are finding this same problem and no one seems to have an answer. With people now saying the old methods no longer work, the best answer anyone else seems to come up with is leave the modem unplugged over night, yet, this doesn't work either. I've gone even one step farther and unistalled the NIC thinking this would clear the data, yet it doesn't work either.

**Clearly Vista and 7 are storing this information, what needs to be said to answer the question is where is it being stored so possibly even an advanced user can go in and manually clear it and allow a new IP to be assigned when the DHCP server is not set up to be authorative enough to deny such a request.**I do have one solution in mind I guess I could try, but it doesn't answer the question, and I shouldn't be forced to go this route. I was thinking in theory I could plug a router into my modem and utilize a local non routable IP on the computer, allow the DHCP server to assign the WAN IP to the router, thus giving me control through my router settings in being able to force the change request and leave Windows always on just a non routable IP.

That should work, but it still doesn't answer the question I'd like to know the answer to for Vista and 7, how do you clear this data so the same IP isn't repeat requested like it seems to be wanting to do? What's even more troubling is I can't even get the answer on a Microsoft owned Windows 7 networking support forum. If Microsoft doesn't even know the answer then who does?

This has to be what's happening...

jreuter:

"Perhaps from Vista on this behavior was added to Windows, though I don't know this to be the case for certain."

The question however still remains, and is unanswered, where is Vista and 7 storing this information so it can be manually deleted to change this undesired behavior?

Tony1967, I'm very confused.  Is your dynamic network connection not working, or is it working but you are bothered by the fact that you cannot force the address to change?

If the latter, the bottom line is that your client has no control over the IP address, the DHCP server does, and there is no guarantee that you will get a different address every time you renew the DHCP lease.  That's entirely up to the DHCP server, and it can cache simple things like your MAC address to try to give you the same address each time if someone so chooses to implement a policy like that (I don't run DHCP servers so I don't know what sorts of policies are typically available).

All you can really do on the client end is force expiration and renewal of your DHCP lease.  That offers no control on what address gets assigned to that lease.

What kind of ISP do you have (cable, DSL, ...) and where is the DHCP server?  For example, some modems are both a modem and a router, so the modem is the DHCP server for your local private address space (192.168.*.* or the like), and in that case the DHCP address between the ISP head end and your end stops at the modem/router.  In other cases, where you have a pure modem, the ISP head end DHCP address shows all the way through to your computer.  (Does your modem allow multiple systems to connect through a dumb switch?  If so, then it's likely got router behavior in it.)

Followup: I was still bugged by the difference you observed between Vista/Win7 and XP/LINUX.

Turns out the DHCPDISCOVER message allows a client to request its last known IP address.  The DHCP server may or may not grant that request.  Perhaps from Vista on this behavior was added to Windows, though I don't know this to be the case for certain.

http://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol

The bottom line remains: DHCP gives you no way to force an address change, and never has.  The fact that you got that behavior in some cases is nothing more than a side effect of multiple client and server implementation choices.

Jim

Here is how to change your ip address manually  (or set it to dynamic) on windows 7 (and probably similar in vista):

The Quicker method:

-in the icon tray in the bottom right of the screen, click on the icon that represents your internet connection

-Then click "Open Network and Sharing Center"

-On the left hand menu, click "Change adapter settings"

-right click on your wireless connection and click "Properties"

-Highlight "Internet Protocol Version 4" and click "Properties"

-To set ip address dynamically, click "Obtain an ip address automatically" and "Obtain DNS server address automatically"

Alternative:

-go to start->control panel

-in the search bar, it should say: "Control Panel -> All Control Panel Items"

-click on "Control Panel"

-This should take you to a screen with headings like System and Security, Network and Internet, Hardware and Sound, etc

-Under Network and Internet, click "View network status and tasks"

-On the left hand menu, click "Change adapter settings"

-right click on your wireless connection and click "Properties"

-Highlight "Internet Protocol Version 4" and click "Properties"

-To set ip address dynamically, click "Obtain an ip address automatically" and "Obtain DNS server address automatically"

Is there another forum somewhere that has people who actualy know Microsoft software and can answer what should be a simple question?