Articles
In-depth articles on CIDR notation, subnetting, private IP ranges, AWS VPC design, cloud networking, and network engineering — published regularly as new topics come up.
Looking for quick reference material? The Guides section has concise how-to pages on specific topics. These articles go deeper — more context, more background, more real-world application.
Classful vs Classless: The History That Changed IP Addressing Forever
Before CIDR, every IP address belonged to a fixed Class A, B, or C network. The shift to classless routing in 1993 saved the internet from running out of address space years earlier than it did.
What Is a /32 Host Route and When Should You Use It?
A /32 CIDR block contains exactly one IP address. It is used in firewall rules targeting a single host, BGP loopback advertisements, and AWS security group allowlists for individual IPs.
How Cloud Providers Publish Their IP Ranges (and Why You Should Monitor Them)
AWS, Google Cloud, and Azure all publish their IP ranges as machine-readable JSON feeds. Security teams use these to allowlist traffic, detect exfiltration, and stay ahead of IP space changes.
What Is 169.254.0.0/16? The Link-Local Address Range Explained
Seeing a 169.254.x.x address on your network interface is a sign that something went wrong with DHCP. This range — defined in RFC 3927 — is assigned automatically when no DHCP server is reachable.
Docker Networking: Understanding the Default 172.17.0.0/16 Bridge
Docker assigns containers addresses from the 172.17.0.0/16 range by default. This sometimes conflicts with corporate networks — understanding why helps you reconfigure it correctly.
AWS Reserved IPs: Why Every Subnet Loses 5 Addresses
In every AWS VPC subnet, five IP addresses are reserved by AWS and cannot be assigned to EC2 instances. If you plan subnets without accounting for this, you will run out of addresses sooner than expected.
Why Your Router Uses 192.168.x.x and What That Actually Means
Almost every home router assigns addresses from the 192.168.x.x range. This is not accidental — it is one of three private IP ranges defined by RFC 1918, and understanding it explains how your whole home network works.
Subnetting Cheat Sheet: /8 Through /32 Reference Guide
A quick-reference guide to every CIDR prefix length from /8 to /32 — total IPs, usable hosts, subnet masks, and common use cases for each.
How to Configure AWS Security Groups Using CIDR Blocks
AWS security groups use CIDR notation to define which IP ranges can reach your resources. Getting these rules right is the difference between a secure deployment and an exposed one.
The Three Private IP Ranges Every Network Engineer Should Know
RFC 1918 defines three address blocks reserved for private networks: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. Here's when to use each and why they exist.
CIDR Notation Explained: What the Slash Really Means
CIDR notation compresses two pieces of information — an IP address and a subnet mask — into a single readable string. Here's exactly what that slash number means and why it replaced classful addressing.