How to identify two hosts having same IP

[KADRI]

I installed at my office a sniffer on a host in order to see just what's happening on the network in order to detect broadcasts etc. And I had a packet indicating a duplicate ip on the network. In short I have two hosts (one server) that have the same ip.

My problem is the following:
I have the ip of the two hosts (for that is the same), I have their MAC address (sent by my sniffer), I identified one of the hosts, and I would identify the second (in order why it has the same address and if this is normal or to change where it would not).

So my question is simple: Do you know a way to retrieve the NetBIOS name of a host from its MAC address? Note that I can not stop the server, or at least change their ip.

[Lemog]

If your switches are manageable, you should be able to recover the correspondence between MAC address and switch port. Otherwise, you can not connect a MAC address to a hostname. Otherwise, you can try to sniff all packets from this MAC address and find the info of hostname in specific frames.

[Zachary]

Just refer to below link to identify the manufacturer of your hardware corresponding to mac address:

http://standards.ieee.org/regauth/oui/oui.txt

But as stated above is best to continue to sniff only filters in this mac address and wait for more info. Do you have only Windows machines on your LAN?

And your 2 network cards must be configured in a team or to aggregate the speed to failover.

[KADRI]

Thank you for the info for Mac / manufacturer. I found the brand of machine that also happens to be I think a server, see the same as this two-card networks to ensure connectivity in case of failure of a switch. But I did not expect to see on the network. On your side is that my hypothesis makes sense?