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Calculate IPv4 subnet information including network address, broadcast address, first/last host, and number of hosts from CIDR notation.
Subnet Calculations:
Subnet Mask = 32-bit mask from CIDR prefix length
Network = IP AND Subnet Mask
Broadcast = Network OR Wildcard Mask
Usable Hosts = 2^(32-CIDR) - 2
CIDR (Classless Inter-Domain Routing) notation represents an IP address and its network prefix. For example, 192.168.1.0/24 means the first 24 bits are the network portion and the remaining 8 bits are for hosts.
A subnet mask is a 32-bit number that divides an IP address into a network portion and a host portion. /24 corresponds to a subnet mask of 255.255.255.0.
The network address (first address in the range) identifies the subnet itself and cannot be assigned to a host. The broadcast address (last address) is used to send messages to all devices on the subnet.
A /24 subnet has 256 total addresses (2^8). Subtracting the network address and broadcast address leaves 254 usable host addresses.
Private IP ranges are: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. These are not routable on the public internet and are used for internal networks.
The wildcard mask is the inverse of the subnet mask. It is used in access control lists (ACLs) on Cisco routers and in OSPF configurations to specify which bits of an IP address to match.