Use this network utility to parse, normalize, convert, or derive IPv4, IPv6, subnet, reverse-DNS, or MAC addressing information under a stated prefix convention.

IPv6 address

IPv6 address in RFC 4291 notation, optionally with an embedded IPv4 tail.

Prefix length

Prefix length between zero and one hundred twenty-eight.

Expand an IPv6 address, apply a prefix length, and derive the first address, last address, and exact address count. IPv6 has no broadcast address and does not subtract network or broadcast addresses from a prefix. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Expanded address

The input address in full eight-group lowercase form.

First host

First address in the prefix (the address with all host bits cleared).

Host bits

Number of bits available for host addressing.

Host count

Exact decimal address count as text so prefixes with more than fifty-three host bits stay precise.

Last host

Last address in the prefix (the address with all host bits set).

Network address

The address with all host bits cleared.

Prefix length

Echo of the applied prefix length.

• Syntax and arithmetic validity do not establish reachability, ownership, routing, DNS, privacy, or authorization. IPv4 special-use ranges, IPv6 scopes and compression, prefix boundaries, mapped forms, and host-count conventions require explicit handling.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Validate against current IANA registries and the target platform, test boundary prefixes, and use live network tools only with appropriate authorization.

• EUI-64 IPv6 Link-Local Address Builder

  Derive a modified EUI-64 IPv6 link-local address from a 48-bit MAC by inserting FF:FE and flipping the universal/local bit. Privacy-address schemes use a different method.

• IPv4 Broadcast Address Calculator

  Compute an IPv4 broadcast address from an address and subnet mask.

• IPv4 Usable Host Count Calculator

  Compute assignable IPv4 host addresses from a CIDR prefix, including /31 point-to-point and /32 host routes.