Field notes.
Short, opinionated writing about the things we keep tripping over. No marketing, no listicles.
- DNS2026-04-22
Understanding DNS propagation
Why a DNS change takes hours to roll out — and what's actually happening in the global resolver cache during that time. The real mechanics of TTL, recursive resolvers, and how to verify your records have landed.
- security2026-04-15
Port security basics, the short version
A pragmatic field guide to what ports to keep closed, what to monitor, what to do when something unexpected is listening, and the three audits every network admin should run quarterly.
- networking2026-04-08
Subnet mastery, the short version
Stop counting bits in your head. The four numbers worth memorising about IPv4 subnetting, how CIDR actually works, and how to spot common subnet mistakes in production networks.
- networking2026-04-01
MAC address forensics for non-investigators
What a MAC address tells you about a device on your network — and what it stops telling you the moment macOS, iOS, or Android randomises it. A field guide to OUI lookups, vendor identification, and the limits of MAC-based tracking.
- networking2026-03-25
Beyond ping — five better signals for "is it up"
ICMP is one signal out of many. Here are five other connectivity checks that actually tell you whether your service is reachable, plus when each one matters.