Question

Short answer:

What bits are being masked by the subnet mask, explain why they are masked?

Answer 1

A subnet mask is 32 bit number that mask IP address. It separates IP addresses into network and host addresess. Netwrk bits are consisting with all 1's and Host Bits are all 0's. Zero address are assigned to the network addess and 255 address are assigned to broadcast address. Let an IP address 255.255.255.0 is converted into 11111111.11111111.11111111.00000000 in binary. The main reason of subnetting an IP network is to seperate a big network into smaller multiple networks for better organization or security reasons.