how-to
Guides for the things that keep breaking.
DNS, TLS, ports, headers. Short, practical, fix-oriented. No filler.
- DNS2026-04-20
How to perform a DNS lookup
Resolve a domain to its A, AAAA, MX, TXT, or other records — step by step.
- security2026-04-13
How to check open ports on a host
Verify which TCP ports are reachable on a server, fast.
- security2026-04-06
How to verify an SSL certificate
Inspect the chain, issuer, and expiry of a TLS certificate without reaching for openssl.
- encoding2026-03-30
How to decode Base64
Round-trip a Base64 string back to plain text, or encode text for safe transport.
- networking2026-03-23
How to calculate a subnet
Get network, broadcast, host range, and mask from any IPv4 CIDR — without bit-counting in your head.