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

Anonymous
2009-12-10T08:06:48+00:00

Had same issue on Vista, upgraded to Win7 and issue remains.

I have a Dynamic ISP IP address, yet it remains as if it were static, everything that use to work in XP and previous versions of Windows no longer works in Vista or 7. I spoke to my ISP (3 times, 3 different techs), they said my IP is dynamic and confirmed it is not set by them as static. They charge more for a static IP, so would not just be giving me this "upgrade" for free. They had "no idea" how to force/change a new IP address in Vista or 7.

PLEASE! Do not bother suggesting to run ipconfig /flushdns, /release, /renew at a prompt to do this like every internet search suggests, THIS DOES NOT WORK. This was done with cmd prompt opened under "Run As Administrator".

PLEASE! Read everything I have already done here before suggesting something I've already tried or have tested and proven to work/not work.

Here are other things I have tried, THAT ALSO DO NOT WORK:

(NOTE: no router is being used, direct connected, CAT5, PC NIC to broadband modem)

-Left modem unplugged 72 hours. No change

-Had ISP send me a new modem. No change

-Uninstalled Network adapter. No change

-Changed IP4 settings from "Obtain Auto" to a made up forced IP, rebooted, then changed back to auto. No change

So, with all of this "old school" stuff already tried and failed, what have they changed in Vista and 7 that seems to keep even Dynamic IP's as static? Where is Windows caching or storing this information so I can clear it, none of the traditional methods work. I absolutely can not stand having a static IP on my home computer.

If you internet search this exact question you'll find what I have, everyone is suggesting the once working methods I've already tried above, yet people using Vista or 7 are repeatedly finding this no longer works.

Here's some more information, that confirms the IP isn't being stored in my modem, or assigned to the MAC address of my NIC...

If I boot this same PC to a LINUX Live type CD, using the same MAC address and NIC it obtains a different IP address everytime it reboots. The issue clearly has nothing to do with my ISP, modem, or PC in general.

If I hot swap my modem to a different PC, the other PC gets a fresh (different) IP address. If this other PC is using XP I can force the ipconfig /release /renew to change its IP address.

If the different PC is running Vista, the IP remains static no matter what I try unless the hard drive is wiped and Vista is reinstalled, then it obtains a new IP on the PC with the clean install, yet it can not be changed after this happens.

So clearly, Windows Vista and Windows 7 are holding onto IP configuration information somewhere and reusing this information when it detects you are using the same internet provider, WHERE is it being stored so I can clear it?

Thank you so much if you have a working solution and actually know the answer, instead of just reading what can already be found by a search engine and reposting info that is no longer valid like everyone else on the internet is currently doing when trying to answer this question.

Windows for home | Previous Windows versions | Internet and connectivity

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Anonymous
2011-07-14T20:20:09+00:00

I think I have found a solution. It has worked for me so I guess it might work for you.

  1. Find out your IP address e.g. go to a website like http://www.whatismyip.com/ it will show you your IP.
  2. Copy It.
  3. Open Network & Sharing Center
  4. Open the Properties of the network you what your IP to change. In my case it is a EVDO modem.
  5. On the Networking tab double-click TCP/IPv4 which will open a window to edit IP and DNS IP address.
  6. On this window Click on "Use the following IP address" and paste that IP you copied at Step 2.
  7. Change the last digit of the IP to any value above it e.g. if its 192.168.23.123 edit the last digit to something like 122 so that the IP becomes 192.168.23.122.
  8. Click OK until all the windows close.
  9. Disconnect from that network.
  10. Reconnect to that network and if it goes as planned the ISP should force a Dynamic IP. Check http://www.whatismyip.com/ if it has changed. If you cannot browse go to Step 6 and select "Obtain an IP address automatically" then Disconnect -> Reconnect the network.

This worked for me so I'm not sure if it will work for you. Feedback will be greatly appreciated.

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  1. Anonymous
    2010-01-20T14:53:07+00:00

    The behavior that tony1967 started this thread with will not cause any IP address conflicts.  A DHCP address is a lease with an expiration time.  Win7 caches the address and asks for it again after restart / renew / whatever, but Windows just uses this to request the same address.  The DHCP server still has the authority to grant or deny that request if the address has already been taken by another system.  If Win7 is still using the address without asking DHCP first, it would be because the lease hasn't expired. 

    I've never seen Win7 get this wrong and start using duplicate addresses.  I have seen some older non-win7 cases on some older virtual machine platform where a virtual machine would restart and not realize it's addresses had expired and cause address conflicts, but I haven't seen this with Win7 on VMs.

    Jim

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  2. Anonymous
    2010-01-20T09:37:39+00:00

    Windows 7 get a dynamic IP address but seems to cache last used IP address

    so if this cached IP address was alloated to an other machine

    the IP conflict is there....   2 machines trying to use same IP address

    I do want Windows 7 to allocate a new free IP address and not reuse the cached one....

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  3. Anonymous
    2010-01-15T14:12:35+00:00

    Why would things "not work" with a static IP address? What "things"?

    If you find my response helpful, please click on the "Vote as Helpful" button!Thank you! My Blog

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  4. Anonymous
    2010-01-15T14:01:38+00:00

    Me, a newbie pops up.... I use wireless network since long First Vista machine in network half a year ago First windows 7 machine a month ago alone on the network BUT running both machines at the same time I get IP conflict and all machines miss the connections... I thought dynamic address should prohibit this !!!!!!

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