Practical cheat sheets for system administrators and infrastructure engineers.
Quick reference tables for networking, DNS, PowerShell, Linux permissions, ports and more.
Networking
DNS record types
Quick reference for common DNS record types including A, AAAA, CNAME, MX, TXT, NS and others used in infrastructure and cloud environments.
Subnet mask
Quick reference for subnet masks, CIDR notation, usable hosts and common IPv4 subnet ranges used in network administration.
Common network ports
Quick reference for common TCP and UDP ports used by SSH, DNS, HTTP, HTTPS, RDP, SMTP, LDAP and other core services.
Infrastructure
PowerShell commands
Quick reference for useful PowerShell commands used in Windows administration, automation and system troubleshooting.
Linux permissions
Quick reference for Linux file permissions, numeric chmod values, symbolic notation and common permission patterns.
Web
HTTP status codes
Quick reference for common HTTP status codes including 200, 301, 400, 403, 404 and 500 with practical meanings.