SIMPLE SYSTEMS / QUICK REFERENCE
12 printable, one-page cheat sheets for common system administration tasks. Each PDF includes reference links and a small, neutral link back to simplesys.dev.
All 12 cheat sheets
A 12-page A4 PDF. Free to download, keep or print.
Active Directory diagnostics
Practical AD DS checks for DC discovery, DNS, replication, time and event logs.
Download PDFBackup & recovery
RPO/RTO, retention, protected copies, capacity planning and restore testing.
Download PDFCommon network ports
Common service ports, TCP/UDP distinctions and practical connectivity checks.
Download PDFDNS quick reference
Common record types, dig and PowerShell queries, caching and troubleshooting.
Download PDFE-mail authentication
Mail routing, authentication, alignment and a practical diagnostic checklist.
Download PDFGroup Policy troubleshooting
RSoP reports, policy scope, processing order, operational logs and targeted refreshes.
Download PDFIPv4 subnetting
Common IPv4 masks, host counts, private ranges and subnet arithmetic.
Download PDFLinux diagnostics
Read-only Linux commands for interfaces, sockets, storage, systemd and logs.
Download PDFMicrosoft 365 mail troubleshooting
Message trace, nondelivery reports, DNS, authentication and escalation evidence.
Download PDFPowerShell diagnostics
Practical Windows network, service, process, event and file integrity commands.
Download PDFRAID and storage
RAID levels, capacity formulas, failure tolerance, spares and storage sizing.
Download PDFWindows event logs
Important log channels, severity levels, PowerShell filtering and EVTX exports.
Download PDFEdition 1.2 · Reviewed 29 October 2026. Commands and examples should be adapted to your environment. Reference links are included inside each sheet.