Hey guys i have a question regarding the network. Our network was down and it was saying " The network has IP address conflict" and none of the IP addresses in our network were the same......How can you do that??????? We are haing Windows server 2008 and then a couple of Netgear switches. Thanks Bharat

It is unlikely that you would get that message and not have a conflict. Can you try disconnecting various network segments or devices from the switch to isolate. Also if you have a VPN make sure there is no overlap with assigned IP's. Though it shouldn't happen it is possible a DHCP device has been assigned the same IP as a statically assigned device such as a printer.Rob Williams

It is unlikely that you would get that message and not have a conflict. Can you try disconnecting various network segments or devices from the switch to isolate. Also if you have a VPN make sure there is no overlap with assigned IP's. Though it shouldn't happen it is possible a DHCP device has been assigned the same IP as a statically assigned device such as a printer. Rob Williams It might help your troubleshooting in the future to keep an active document of your IP Schema. Example: IP Address Schema Network: 172.16.0.0 Range: 172.16.0.1 - 172.16.1.254 Bcast - N.1.255 Reserved Network Devices 172.16.0: 1-10 255.255.254.0 Static Only Reserved Servers 172.16.0: 10 - 100 255.255.254.0 Static Only Reserved Device Type1 172.16.0: 101-200 255.255.254.0 Static Only Reserved Device Type2 172.16.0: 201-254 255.255.254.0 Static Only Distribution Local 172.16.1.0-200 255.255.254.0 MemSrv1 Distribution VPN 172.16.1.201.254 255.255.254.0 EdgeSrv1 172.16.0.10 DC1 255.255.254.0 static 172.16.0.11 DC2 255.255.254.0 static 172.16.0.12 Exch1 (Edge Srv) 255.255.254.0 static 172.16.0.13 Exch2 (Hub Xport) 255.255.254.0 static 172.16.0.14 Moss001 255.255.254.0 static 172.16.0.101 Printer001 255.255.254.0 static 172.16.0.201 NetStor001 255.255.254.1 static Obviously this would go in a spreadsheet and you might have different sheets for different reservation types but to keep track of what you have and don't have will help you easily resolve Networking Issues pertaining to the IP Conflict you're describing. If financing allowed it, I would even have VPN users using a seperate subnet than your local subnet. Best Regards, Steve Kline Microsoft Certified IT Professional: Server Administrator Microsoft Certified Technology Specialist: Active Directory, Network Infrastructure, Application Platform, Windows 7 Microsoft Certified Product Specialist & Network Product Specialist Red Hat Certified System Administrator This posting is "as is" without warranties and confers no rights.

I agree whole heartedly. However, I prefer to use the DHCP management console with reservations and exclusions so that there is a dynamic list. It is just a different approach but I find documentation falls behind. I only have servers with Static IP's and they are in a specific range with a DHCP exclusion, all other devices that would normally be assignee static IP's such as printers or 'special' PC's receive a DHCP leas via a reservation. You can even create a DHCP reservation for a statically assigned device such as a server even though it will never use it. This way all devices are visible in the DHCP addresses lease list, current, centrally managed, and easily changed. Just food for thought in the future.Rob Williams

It is unlikely that you would get that message and not have a conflict. Can you try disconnecting various network segments or devices from the switch to isolate. Also if you have a VPN make sure there is no overlap with assigned IP's. Though it shouldn't happen it is possible a DHCP device has been assigned the same IP as a statically assigned device such as a printer. Rob Williams It might help your troubleshooting in the future to keep an active document of your IP Schema. Example: IP Address Schema Network: 172.16.0.0 Range: 172.16.0.1 - 172.16.1.254 Bcast - N.1.255 Reserved Network Devices 172.16.0: 1-10 255.255.254.0 Static Only Reserved Servers 172.16.0: 10 - 100 255.255.254.0 Static Only Reserved Device Type1 172.16.0: 101-200 255.255.254.0 Static Only Reserved Device Type2 172.16.0: 201-254 255.255.254.0 Static Only Distribution Local 172.16.1.0-200 255.255.254.0 MemSrv1 Distribution VPN 172.16.1.201.254 255.255.254.0 EdgeSrv1 172.16.0.10 DC1 255.255.254.0 static 172.16.0.11 DC2 255.255.254.0 static 172.16.0.12 Exch1 (Edge Srv) 255.255.254.0 static 172.16.0.13 Exch2 (Hub Xport) 255.255.254.0 static 172.16.0.14 Moss001 255.255.254.0 static 172.16.0.101 Printer001 255.255.254.0 static 172.16.0.201 NetStor001 255.255.254.1 static Obviously this would go in a spreadsheet and you might have different sheets for different reservation types but to keep track of what you have and don't have will help you easily resolve Networking Issues pertaining to the IP Conflict you're describing. If financing allowed it (meaning more hardware), I would even have VPN users using a seperate subnet than your local subnet. Best Regards, Steve Kline Microsoft Certified IT Professional: Server Administrator Microsoft Certified Technology Specialist: Active Directory, Network Infrastructure, Application Platform, Windows 7 Microsoft Certified Product Specialist & Network Product Specialist Red Hat Certified System Administrator This posting is "as is" without warranties and confers no rights.

Hi Bharat, Please post us event log from DHCP server that popup ip conflict message. Troubling shooting with "arp -a" commend if DHCP set reservations not work Resolving Duplicate IP Address Conflicts on a DHCP Network http://support.microsoft.com/kb/133490 How to Troubleshoot Duplicate Media Access Control Address Conflicts http://support.microsoft.com/kb/164903Regards, Rick Tan