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Community Member

Strange Ping response

Hi,

Station X had 66.78.16.72 IP address. And this IP address has changed to 66.78.16.92 after the DHCP lease expired.

When I ping 66.78.16.72 from 204.102.3.45 I get ping responses from 66.78.16.92. Can some body explain this phenomenon.

TIA

2 REPLIES
Community Member

Re: Strange Ping response

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

Hall of Fame Super Gold

Re: Strange Ping response

Kalyan

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.

HTH

Rick

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