How To: Fix-Windows Vista Fails To Obtain IP Address From DHCP Server/Router
Windows Vista changes the behavior of the DHCP Client (Compared to Windows XP SP2), and now tells the server to respond using broadcast (multicast instead of unicast). This change allows Windows Vista to obtain an IP address even if not connected to the same subnet as the DHCP server.
Sometimes your Windows Vista will fail to obtain an IP Address from a DHCP(Dynamic Host Configuration Protocol) server like your Broadband or Wireless router. Disable the DHCP BROADCAST flag in Windows Vista is the only resolution.
You can Disable the DHCP BROADCAST flag in Windows Vista by a simple registry modification.
- Run the Windows Vista registry editor by type regedit in the Start Search box, and then press ENTER.
- Locate and then expand the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\{GUID}
Note: In this registry path, click the (GUID) subkey that corresponds to the network adapter that is connected to the network.
- Go to Edit, point to New, and then click DWORD (32-bit) Value.
- Name the new DWORD as DhcpConnEnableBcastFlagToggle.
- Right-click DhcpConnEnableBcastFlagToggle, and then click Modify.
- In the Value data box, type 1, and then click OK.
- Close Registry Editor.
By this setting Windows Vista will first try to obtain an IP address by using the BROADCAST flag in DHCP Discover packets. If that fails, it will try to obtain an IP address without using the BROADCAST flag in DHCP Discover packets.
If you know the router or the non-Microsoft DHCP(Dynamic Host Configuration Protocol) server does not support the DHCP BROADCAST flag,then do the following registry alteration:
- Run the Windows Vista registry editor by type regedit in the Start Search box, and then press ENTER.
- Locate and then expand the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\{GUID}
- Go to Edit, point to New, and then click DWORD (32-bit) Value.
- Name the new DWORD as DhcpConnForceBroadcastFlag.
- Right-click DhcpConnForceBroadcastFlag, and then click Modify.
- In the Value data box, type 0, and then click OK.
- Close Registry Editor.
After you set this registry entry, Windows Vista never uses the DHCP BROADCAST flag.
Warning: Modifying the Windows registry can cause serious damage to your Windows Operating System.It is better to backup your Windows registry data before making any changes. Tomstricks.com is not responsible for any changes you may make to your system.
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Written by Tony on May 2nd, 2009 with
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