On Sat, Jan 14, 2012 at 8:57 AM, Marc Deop damnshock@gmail.com wrote:
ARP: In a traditional ethernet network, when you try to connect to a machine on your local network with the number 10.20.30.40 then your machine will send out an ARP broadcast packet "whois 10.20.30.40" and then the machine in question will respond with its MAC address and then the machines can talk via ethernet.
Ain't it the router the one that responds?
No, the device with the IP responds directly.
I mean, it usually has an ARP table to speed up things ;)
Everything keeps an arp cache so they don't have to repeat the lookup for every packet, but routers expect to talk to a lot of devices and hold the cached pairs longer - perhaps up to 20 minutes. Most other devices have very short timeouts so they'll notice an IP change more quickly.