2. Network address

3. Host address

5. Subnet Mask - 32 bit mask ( 1’s followed by 0’s ) - Used by routers and hosts to determine the number of network- significant bits ( identified by 1’s ) and host- significantbitsin an IP address (identified by 0’s) - example : ClassNetwork AddressDefault subnet mask A 12.0.0.0 255.0.0.0 or /8 B 172.16.0.0 255.255.0.0 or /16 C 192.168.0.0 255.255.255.0 or /24