On one network device I've come across, when I check the arp table, I see an entry for the broadcast MAC address:
FF:FF:FF:FF:FF:FF 192.168.1.255
Is this entry normal to find in an arp table? I just tried a broadcast ping to 192.168.1.255 on my linux box (NOT the network device in question), and when checking the arp table, I see entries for all the devices that replied by not the broadcast address above.
As I understand it, devices use the arp table to lookup the MAC address of a device they want to talk to so that they know what to fill in the layer 2 destination address with. If the entry doesn't appear in their arp table, they send an arp broadcast to figure it out and temporarily add it to their arp table. Why would a device ever need an entry for FF:FF:FF:FF:FF:FF in its arp table? Shouldn't any device be able to easily figure out if a given IP is a broadcast address by looking at its IP address and netmask? If a given IP is a broadcast IP, the destination MAC address should always be FF:FF:FF:FF:FF:FF - it doesn't really need to consult the arp table for that, does it?
