FreeTools Labs Glossary
IP addresses and subnets
Learn how IP addresses and prefixes structure networks, and how CIDR, subnet masks and address ranges relate.
Relevant tool
Subnet analysis turns an IP address and prefix into a network boundary, address range and host capacity; the prefix determines which bits belong to the network.
Functions and inputs
Analyse accepts IPv4 or IPv6 with a prefix, and IPv4 also accepts a contiguous dotted mask. Split normalizes a parent prefix and exposes an indexed range of smaller child prefixes.
Calculation model
IPv4 masking and IPv6 prefix length define the address relationships used by the analysis and split modes: IPv4 network = address AND mask; host bits = 32 − prefix; IPv6 address space = 128 bits.
How the calculator model works
IPv4 normal output includes network, mask, wildcard, broadcast and host range; /31 and /32 are handled as their own cases without the usual two-address deduction. IPv6 displays compressed and expanded forms, first and last addresses and has no broadcast; large counts remain exact BigInt values.
Checked examples
These checked addresses demonstrate a regular IPv4 subnet, the /31 and /32 cases, an IPv6 prefix and a subnet split: 192.168.10.73/26 → 192.168.10.64/26; 64 total, 62 usable. 192.168.1.10/31 → 2 usable, broadcast: —; /32 → 1 usable. 2001:db8:abcd:1234:5678::1/64 → 2001:db8:abcd:1234::/64; /24 → /27 = 8.
Units, display and interpretation
CIDR, dotted masks, wildcards and compressed IPv6 notation describe the same addressed structure from different views: CIDR · dotted mask/wildcard · IPv4 host range · IPv6 compressed/expanded form · exact BigInt counts.
Scope and limits
The local calculator does not query DNS, WHOIS, ASN, GeoIP, ping or a live network. A split is indexed and deliberately materializes only a bounded number of entries, not an unlimited address plan.