Subnet Calculator — IPv4 & IPv6
Articles, guides, and in-depth tips for the Subnet Calculator — IPv4 & IPv6 — everything you need to get the most out of it.
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Why a /16 Network with 65,534 Addresses Is Often the Wrong Design — Broadcast Domains, Segmentation, and VLSM
Subnetting Math: Why /24 Gives 254 Hosts, How VLSM Works, and What the Slash Actually Means
A /24 gives 254 usable hosts, not 256 — because subnetting always reserves the first address (network) and last address (broadcast). Here's the 2^n−2 formula across all prefix lengths, VLSM (Variable Length Subnet Masking) for efficiently dividing address space into different-sized subnets, why route summarization (supernetting) is the reverse operation, and what the slash number in CIDR notation actually means in binary.
IPv6 Address Types: Why One Interface Has Link-Local, ULA, and Global Addresses All at Once
A single IPv6 interface normally has 3-4 different addresses simultaneously — link-local, unique local (ULA), and one or more global unicast addresses, each with different scope and purpose. Here's what each address type does, why ULAs exist alongside global addresses unlike IPv4's NAT model, and why privacy extensions cause global addresses to rotate.
Cloud VPC Design: Public vs Private Subnets, NAT Gateways, and the Three-Tier Architecture
AWS VPCs, GCP VPCs, and Azure VNets follow the same three-tier pattern — public subnets for internet-facing resources, private subnets for application and data tiers. Here's the terminology across providers, NAT Gateway mechanics, VPC peering, and the four most common cloud network design mistakes.
Subnetting Explained: CIDR Notation, Host Counts, and Practical Network Design
CIDR notation and subnetting make more sense once you see the pattern: each /1 increase halves the subnet. Here's how prefix lengths translate to host counts, common use cases from cloud VPCs to point-to-point links, and IPv6 subnetting philosophy.
Subnet Calculator — IPv4 & IPv6 Network Address, Host Range & CIDR
Learn how IPv4 subnetting works, what CIDR notation means, how to calculate network addresses, host ranges, and usable hosts, with real examples — plus an IPv6 intro and a free subnet calculator.
