DHCP IP Conflict

Discussion in 'Windows 7 Networking' started by kgrohs, Mar 31, 2010.

  1. kgrohs

    kgrohs New Member

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    I have 14 computers set to DHCP and since I upgraded them to Windows 7, I intermittently get an IP Conflict error. Once this happens I have a very difficult time getting the computer to reconnect to the network. I've tried rebooting, removing the network cable, rebooting the ISP's modem, setting a fake static IP then going back to dhcp, entering ipconfig /release, but nothing works except time. I am hoping for two things.
    1)at the least, how clear the DHCP IP address so that the PC can reconnect to the network,
    2) and at best, the appropriate Windows & network settings to keep the problem from happening again.
    Thanks!
     
  2. Trouble

    Trouble Noob Whisperer

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    What is hosting DHCP on your network?
    If it's a router then perhaps look to the manufacturer and see if there is an available firmware update for that particular model number and version number.
    Alternately you might try disabling IPv6 on the Win7 machines just to see if it's possibly causing problems for the router with DHCP solicitations for IPv6. Just a thought.
     
  3. kgrohs

    kgrohs New Member

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    I will contact our provider to ask that they update their firmware. In the meantime, I've unchecked V6 but still cannot reconnect. Is there a way to disconnect the exisiting DHCP IP address on the PC so that it can find a new address?
     
  4. Trouble

    Trouble Noob Whisperer

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    command prompt
    ipconfig /release (should release all active DHCP leases from the local machine)
    ipconfig /all (should confirm that all DHCP addresses are now 0.0.0.0)
    ipconfig /renew (should appropriate a new DHCP lease)
    ipconfig /all (should confirm new lease address)
    How long is the DHCP device leasing addresses for (you may want to adjust this time, try shorter lease times, maybe 1hour)
    How large is the lease pool? Make sure, if there are computers or other network nodes (servers or printers) with static IP addresses that they have an exception created within the pool, or better yet, that they are addressed outside the scope pool.
    Make sure that if the computers have multiple network adapters (wired and wireless) that you pick one and disable the other and of course make sure that there is not a second device on the same network, capable of handing out DHCP addresses (a second wireless router, or wireless router in an adjacent office)
    Are all these problem machines hard wired to the network? Do any of them have built in wireless devices? (Laptops, and even some new desktops now come with built in wireless cards)
     

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