What is the difference between network address and first usable host?

The network address (with all host bits set to 0) identifies the subnet itself. The first usable host address is always network + 1 (for standard subnets /30 and larger), used to assign IP addresses to servers, routers, and client devices.

What is the maximum number of IPs this tool can expand?

The tool can comfortably enumerate up to 65,536 IP addresses (a full /16 subnet) in fractions of a second directly inside your browser memory without lag.

IPv4 Range & CIDR Subnet Expander

Enumerate all usable host IP addresses from CIDR blocks or start-end ranges. Calculates network addresses, broadcast boundaries, netmasks, and wildcards with 1-click text, JSON, or CSV export. 100% private in-browser.

Subnet Enumeration Architecture

Firewall & ACL Rule Generation

Enumerating host lists makes it simple to feed explicit IP ranges into web server configs (Nginx/Apache allow directives), cloud security groups, or router access lists.

CIDR Bitmask Arithmetic

Evaluates network boundaries using 32-bit unsigned bitwise shifting, guaranteeing exact compliance with RFC 4632 classless inter-domain routing standards.

Safe Browser Memory Guard

Large subnets like /16 are streamed directly into an optimized string buffer, rendering tens of thousands of addresses in milliseconds without freezing your browser tab.