how locate a duplicate ip?

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Jul 3rd, 2007
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i was told by one of LAN Admins that a security camera (installed by another firm) has a duplicate IP. I'm asking to get this guy back to show us what he saw where. In the meantime, is there a way to locate a duplicate?

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jainvarun Tue, 07/03/2007 - 09:07
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ja1064 Tue, 07/03/2007 - 09:18
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i wasn't clear. this security tech left a message for our guy that he saw some message about a duplicate ip but didn't explain where he it saw nor what device. I made the obvious request for him to explain what he saw where. Long story but our guy has been replaced so the new guy is asking about this.

so, when you don't know where the device is, is there some method, tool to find it. btw, our dhcp server is netware; we do not have active directory

sundar.palaniappan Tue, 07/03/2007 - 09:48
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There may be more than one way to do it but here's one of the ways you may be able to identify the device(s) with the duplicate IP address.

The router, that's the gateway for the subnet, may log a duplicate address error message. Do a 'show ip arp ' and note the MAC address down. Issue the command 'clear ip arp ' and do 'show ip arp ' again and you may see a different MAC address. The MAC address may be alternating between the two devices. Sometimes you may have to clear the ARP entry multiple times to identify the device that's got the duplicate address.



ja1064 Fri, 07/06/2007 - 11:51
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is there a way to clear the whole table since i don't know what the address is? The syntax is looking for an address

Jon Marshall Fri, 07/06/2007 - 12:00
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Yes, you don't say what your device is so try

clear arp

clear arp-cache

Note that this will remove all the arp entries which will give a slight performance hit.




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