IP Networking Guides
Practical reference guides on CIDR notation, subnetting, private IP ranges, cloud VPC design, and more. Written for network engineers, DevOps teams, and developers.
Fundamentals
What Is CIDR Notation?
A plain-English explanation of CIDR notation — what the slash number means, how to read it, and why it replaced classful addressing.
Private IP Ranges Explained (RFC 1918)
The three private IPv4 address ranges — 10/8, 172.16/12, and 192.168/16 — explained: why they exist, how NAT enables them, and when to use each.
Subnet Mask vs. CIDR Notation
How to convert between subnet masks (255.255.255.0) and CIDR prefix lengths (/24) — a complete conversion table and the math behind it.
IPv4 Address Classes Explained (A, B, C, D, E)
What the original classful addressing system was, how Class A/B/C/D/E networks differ, and why CIDR replaced it.
How-To
How to Subnet a Network — Step by Step
A practical guide to subnetting: dividing a network into smaller subnets, calculating network addresses, and choosing the right prefix length.
Writing Firewall Rules with CIDR Notation
How to express network access rules using CIDR blocks: allowing a range, blocking a subnet, AWS security groups, iptables, and cloud firewall examples.
Cloud
How to Choose a CIDR Block for Your AWS VPC
Guidance on picking the right VPC CIDR, avoiding conflicts with on-premises networks, sizing subnets per AZ, and planning for growth.
AWS VPC Subnetting Guide
How to design subnets within an AWS VPC: public vs. private subnets, per-AZ sizing, reserved IPs, and common patterns for web, app, and database tiers.
Kubernetes Pod and Service CIDR Planning
How to choose pod-CIDR and service-CIDR for a Kubernetes cluster, avoid conflicts with node and VPC networks, and plan for cluster growth.
Reference
Reserved IP Address Ranges — Complete Guide
Every reserved IPv4 range: loopback (127/8), link-local (169.254/16), CGNAT (100.64/10), documentation ranges, multicast — and what each is used for.
Loopback (127.0.0.1) and Link-Local (169.254.x.x) Addresses
What loopback and link-local addresses are, how they differ, and why 169.254.169.254 is one of the most important IPs in cloud computing.