IP Addressing and Subnets
Every device needs an address — here's how the addressing system works.
Key takeaways
- IPv4 addresses are 32-bit numbers written in dotted-decimal notation.
- Subnet masks (CIDR notation) divide addresses into network and host portions.
- Private IP ranges (10.x, 172.16-31.x, 192.168.x) are not routed on the public internet.
- Understanding subnets helps analysts identify whether traffic is internal or external.
When analysts read firewall logs or packet captures, the first thing they look at are the IP addresses. Understanding subnet math is a core SOC analyst skill.
The private address ranges — 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 — are special: routers on the public internet won't forward them.
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