good question. if i understand you, you are wondering how the remote device knows your subnet mask? the answer is it does not and it doesn't care either.
when you send a packet from your PC to another host in the same network for instance you are saying, "according to my network, defined by my netmask, send this packet to the correct host in the ARP table or send out an ARP broadcast to find the destination for my packet." The packet knows if its destined for a local network or a different network simply by comparing the IP address with its subnet mask. This is what your default GW is for. If it sees by the subnet mask that this address is local it strips MAC info and the netmask and forwards the packet to the default gateway. Then the router uses its routing table to find the correct destination for the packet. A receiving host doesn't care about the netmask, only the IP number from which the packet was received. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=29184&t=29182 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]