Printable reference sheets
Each sheet is designed to look beautiful on screen and print cleanly on letter paper (front and back). Hit ⌘P / Ctrl P on any sheet, or use the Print button.
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IPv4 Subnet Cheat Sheet
Every prefix /0–/32 with netmask, wildcard, hosts, and block size.
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Common TCP & UDP Ports
Well-known ports grouped by category — web, mail, remote, DB, infra.
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Private & Special-Use IP Ranges
IANA special-purpose IPv4 and IPv6 blocks with multicast well-knowns.
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IPv6 Quick Reference
Notation rules, address types, prefix conventions, multicast scopes.
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DNS Record Types
Common, DNSSEC, and modern records plus SOA fields, TTLs, SPF/DKIM/DMARC.