An IPv4 network is a contiguous address block identified by a common prefix. Its key attributes are the network address, broadcast address, first and last usable addresses, and maximum host count. section 7.3.3
For a 192.168.100.0/24 network:
- 192.168.100.0 is the network address and cannot be assigned to a host. section 7.3.3
- 192.168.100.255 is the broadcast address for reaching all hosts on the network. section 7.3.3
- 192.168.100.1 and 192.168.100.254 are the first and last usable addresses. section 7.3.3
- Eight host bits provide 256 total addresses and 254 assignable hosts after reserving the network and broadcast addresses. section 7.3.3
Subnetting a large block
Borrowing 12 bits from 10.0.0.0/8 creates 4,096 /20 subnets. The same five attributes—network, broadcast, first usable, last usable, and maximum hosts—are calculated for each subnet. section 11.2.3
