Strange Ping response

Unanswered Question
Apr 17th, 2007


Station X had IP address. And this IP address has changed to after the DHCP lease expired.

When I ping from I get ping responses from Can some body explain this phenomenon.


I have this problem too.
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danail-petrov Tue, 04/17/2007 - 23:29

Hi there,

i believe this can occurs, if you have proxy-arp enabled on station X interface. You can easy check this using some network sniffer (tcpdump/tethereal).

Kind Regards,

Danail Petrov

Richard Burts Wed, 04/18/2007 - 03:43


The symptoms that you describe sound like an issue with the ARP table. I believe that your router ARP table still has an entry for the .72 address with an associated MAC address. When you ping the .72 address the ping packet is forwarded to the router which sends to the MAC address shown in its ARP table. But when the ping gets to that machine the IP address is now changed. So you get a response from .92 which is the new address associated with that MAC address. If I am correct the ARP entry should age out and the problem should resolve itself. Or you could clear the ARP table on the router to accelerate the process.

ARP issues are fairly common when you are changig addresses on devices in the network.




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