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Date:      Sun, 2 Aug 1998 13:13:55 +1200
From:      "Dan Langille" <junkmale@xtra.co.nz>
To:        freebsd-questions@FreeBSD.ORG
Subject:   arp reports changes in physical address
Message-ID:  <199808020113.NAA02842@cyclops.xtra.co.nz>

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As I was composing this message, I think I found the solution.  I changed 
the IP address of the NIC in question.  And made changes to the DNS zone 
files.  The problem has not recurred in the past 3 hours.

### The original message ###

Still, I would like comments on the following symptoms.

Whenever I power this particular NT (call it NT2) box on my subnet, arp on 
my FreeBSD box reports: "arp: 192.168.0.1 moved from aa:bb:cc:dd:ee:ff to 
11:22:33:44:55:66".  Then the MAC addresses swap back again.

The mailing list archives shows that this problem occurs when two machines 
argue over who has a given IP address.  There's only three machines on my 
subnet, and they each have different IP addresses.  I've just rechecked 
that.

The IP address reported by arp is correct in that 192.168.0.1 is the NT2 
box.  The MAC addresses it is reporting are a mystery to me.  Checking the 
NT2 box reveals that the actual physical address of the NIC is 
aa:bb:cc:dd:ee:ff.

There is no NIC on my subnet with a physical address of 11:22:33:44:55:66.

I note that *sometimes* when I ping the FreeBSD box from the NT2 box, the 
arp message appears, this time displaying the correct MAC for that IP 
address, *and* the ping works.  Later, the alternate message appears and 
the pings fail.

The FreeBSD box acts as the gateway for my subnet and as the server for my 
mini-DNS.  When arp reports the correct MAC, NT2 can ping things via name 
or IP address.  When arp reports the false address for NT2, NT2 cannot 
ping by name but it can ping by address but it cannot ping the FreeBSD box.

Where is this false physical address coming from?  How do I get rid of it?

### end of original query ###

--
Dan Langille
DVL Software Limited
http://www.dvl-software.com/freebsd : my [mis]adventures

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