redzilla
Topic

IP Addressing

Subnets, masks, IPv6, NAT and address planning.

Learn first

Subnetting Without Tears What a mask really is, how to read a /26 at a glance, and how to split a network with VLSM with nothing wasted. ≈ 14 min read → IPv6 for Humans Why IPv6 addresses look so strange, how they compress, which types exist and how to plan your /64s painlessly. ≈ 12 min read → Inside the Internet: Public IPs, NAT & ASNs A packet’s journey from your private LAN to the world: NAT/PAT, public addresses, autonomous systems, and how to investigate any IP. ≈ 11 min read →

14 tools

Subnet Calculator

Compute masks, ranges, broadcast and hosts. Supports VLSM and CIDR notation.

IPv6 Calculator

Expand and compress IPv6 addresses; compute network, prefix, range, number of /64s and address type.

Subnet Mask Converter

Convert between decimal mask, CIDR and binary instantly.

CIDR Aggregator

Summarize subnet lists into supernets and convert between IP range and CIDR list.

CIDR Table

Reference table from /0 to /32: mask, wildcard, hosts, hex and private ranges, instantly filterable.

IP Converter

Convert an IPv4 between decimal, binary, hexadecimal, octal and integer, with a per-octet breakdown.

Wildcard Mask

Convert between mask, CIDR and wildcard (inverse mask) and generate Cisco ACL and OSPF network examples, with a binary breakdown.

DHCP Scope

Calculate the usable DHCP pool of a subnet (minus gateway, exclusions and reservations) and warn of exhaustion by expected clients.

Subnet Overlap

Tell whether two or more CIDR networks overlap, or one contains another or an IP (IPv4/IPv6), to avoid conflicts.

VLSM Planner

Allocate variable-length subnets to your host requirements: split a base network into optimal blocks with no waste or overlap.

Subnet Divider (FLSM)

Split a network into equal subnets by subnet count, new prefix or hosts per subnet, and list them all with range and broadcast.

NAT / PAT Exhaustion

Estimate the concurrent sessions an overloaded NAT (PAT) supports from public IPs and ephemeral ports, and warn of exhaustion.

IPv6 Planner

Split an IPv6 prefix (/48, /56…) into nibble-aligned subnets: how many /64s, site/building/VLAN hierarchy and examples.

ASN Converter

Convert autonomous-system numbers between asplain and asdot (16/32-bit) and tell whether they are public, private or reserved.