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Windows 7: Need utility to find where IP address conflict is.

06 Feb 2012   #1

Windows 7 RTM x86/x64
Need utility to find where IP address conflict is.

What would be the best? I built my network myself and there are no known IP conflicts.

So, some type of network scanner to see what mac is using what IP..

My System SpecsSystem Spec

06 Feb 2012   #2

Windows 7 Home Premium 64-bit

Is this not available in the "attached devices" in your router ? - the table below shows mine with fixed IPs but even with DHCP anything connected to the router should show the IPs and MAC addresses.

Attached Devices

IP Address Device Name MAC Address
1 SHAW3 00:17:C4:AB:E8:49
2 SHAW2 20:7C:8F:2D1:3C
3 UNKNOWN 00:24:8D:F2:EE:53
My System SpecsSystem Spec
06 Feb 2012   #3

Windows 8 Core X64

My System SpecsSystem Spec

07 Feb 2012   #4

Windows 7 RTM x86/x64

It's a win2008r2 network with a class A dhcp server on it.

The dhcp isn't allowed to give out addresses below 100 because that is what I use for my servers. So something is intruding or the error is just wrong.

There is no other router or utility authorized to give ip addresses out on that subnet
My System SpecsSystem Spec
08 Feb 2012   #5

Windows 7 Ultimate x64


Is the IP Conflict error coming up on the Server itself or a workstation? If its the Server then it normally displays the IP conflicting MAC in the Event logs.

The first thing to do would be to do an arp -a and make a note of the arp table. this should show you if anyone is usnig an address outside your DHCP scope as well. When the error comes up again so another arp lookup and see if there is a change in the tables MAC's.

Has there been any new network equipment installed on the network? How many PC's are on the network? If there are less than 10 it maybe easier to go round and check each PC's IP address.

As for an IP Scanner. Angry IP is very simple and effective:
Angry IP Scanner : Home - IP and Port Scanner Tool for Analyzing Networks

My System SpecsSystem Spec
09 Feb 2012   #6

Windows 7 RTM x86/x64

Thanks Dave.

The error is on one of the exchange servers, not the DHCP server. I took the server offline and did an IP scan and it found there was nothing on that IP. It's odd, because it only shows up from time to time. There are 4 IP's in the DHCP scope and right now, all of them are statically assigned anyway. That's why I am more concerned about an intrusion.
My System SpecsSystem Spec
09 Feb 2012   #7

Windows 7 Ultimate x64

When you say they are statically assigned, do you mean that they have static IP addresses and you have created exclusions for them?

Did you do an ARP lookup? Have a look on the Exchange event logs? Can you get a screen shot of the error as well.

Also, do you lose connectivity at all?

My System SpecsSystem Spec
17 Feb 2012   #8

Windows 7 RTM x86/x64

Sorry, was on vacation.

Did an arp -a last time it showed up which revealed nothing.

No, they are statically assigned without exclusions, but they are on the same IP that the reservation is for., 105, 106 and 107. The conflict is

Nope haven't lost any connectivity, not with the active directory or the web. Very odd.

It's one of those IP Address conflict errors that has the triangle sign with a exclamation point through it. It doesn't show up very often but it still rears it's ugly head maybe 1 time per week. The next time it shows up, I'll get a screenshot of it.
My System SpecsSystem Spec

 Need utility to find where IP address conflict is.

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