Every page is a working tool plus its manualA tool plus its manual Shareable results CC BY 4.0

Networking and security, with the working shown

Three deep pages, each a working tool and its manual. Start with the calculator, learn the method on the cheat sheet, then plan your certifications.

Networking basics
01
IPv4 + IPv6 calculator, VLSM planner

Subnet calculator

Network, broadcast, host range and mask as you type, with the binary working shown and cloud reserved addresses.

 02
Printable chart + practice generator

Subnetting cheat sheet and practice

The /8 to /32 chart on one page, how to rebuild it from memory, and unlimited practice questions with answers.
Career
03
Role path and cost planner

Cybersecurity certification roadmap

Pick the role you want and see the shortest certification path, vendor fees with sources, and study time.

Written by , former GFI Software presales lead for firewall, email security and network products. Every calculator result is checked against a reference implementation, every exam fee links to the vendor page it came from, and every check carries its date.