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..

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
1 192.168.0.40 SHAW3 00:17:C4:AB:E8:49
2 192.168.0.50 SHAW2 20:7C:8F:2D1:3C
3 192.168.0.60 UNKNOWN 00:24:8D:F2:EE:53

Try this: SoftPerfect Network Scanner Freeware download and reviews from SnapFiles

Works for me:

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

Hello,

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


Dave

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.

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?


Dave

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. 10.0.0.101, 105, 106 and 107. The conflict is 10.0.0.6

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.