The subnet mask 255.255.255.0 is applied to a packet with a destiation IP address of 10.20.35.12 what subnet is the packet sent to?

Question

e.mccormick · Answer

That would depend on the IP that sent it, where it is in the network at that moment, etc. See this example: http://www.eventhelix.com/realtimemantra/networking/ip_routing.htm

espex · Answer

The octet, 255, in the subnet mask means to match exactly while the 0 provides a range of 1-254 for the host addresses.
If we assume in this case that the question refers to the router on the network, to find the subnet the packet was sent to you just need to do a 1:1 matching of the 255 mask to the ip.

rsmith6559 · Answer

An IP address contains both a network number and a node number.  To split the two, a bitwise and is done.  The NETwork MASK protects the bits of the network number, which is why the network number is always the zero'th address of a network.

The netmask can be flipped with a bitwise not operation, and re-anded with the IP to get the node number.