Latest guides and cheatsheets.
AI
Turn Off Copilot in Office Apps
Where Microsoft's own settings turn Copilot off in Word, Excel, PowerPoint, OneNote and Outlook, what each setting covers, and where it can't be…
Read the guideAI
AI Chatbots at Work
What to keep out of an AI chatbot, how personal and work accounts differ, the privacy settings Claude, Copilot and Gemini document, and where to…
Read the guideActive Directory
Group Policy Guide
How Group Policy works in a single Active Directory domain: local and domain policy, processing order, filtering, the Central Store, backup and…
Read the guideWebsite Hosting & Development
Certificates Explained
What a TLS certificate is and how a browser or server decides to trust one: key pairs, signing requests, the subject and SAN, key usage, chains to…
Read the guideCheatsheet
Mental Subnetting
One printable page for subnetting IPv4 without a chart: the four steps, the interesting octet for each prefix, mask values and increments, powers…
Open the cheatsheetCheatsheet
OpenSSL Certificate Inspection
OpenSSL commands for reading certificates, requests, CRLs and PFX files, checking a chain, matching a key to its certificate, and testing a live…
Open the cheatsheet
Years of hands-on IT experience
Hi, I’m Jeremiah. I write practical IT guides, cheatsheets, and references.
I have more than 20 years of IT experience in public sector and higher education. Everything here comes from that work and is checked against official documentation before it’s published.
Jeremiah Ellington
Founder