Subbing

Rapid-fire practice for networking and sysadmin exams. Every question is generated on the spot and checked with real binary maths, so no two rounds repeat and there is no question bank to memorise. Get one wrong and you get the working, step by step, not just the right answer. No account, no login. Subnetting is free on the web and in the app; one purchase unlocks the other six topics.

Highlights

topics subnetting, IPv6, ports and protocols, VLSM, binary and hex, ACL wildcards, Linux permissions
modes competitive on a five-minute clock, timed ten-question rounds, or untimed and endless
typed competitive answers are typed, not multiple choice, so there is nothing to guess from
solutions every mistake comes back with the full working, plus a scratch pad for doing it by hand
board per-topic global leaderboards with no accounts: the server seeds each round and the client solves a proof-of-work before a score is accepted
stats daily streak, accuracy and weak spots by question type, kept on the device

Built with

Vue 3 and TypeScript, wrapped with Capacitor for the Android app, on Firebase for hosting, functions and analytics, with purchases through RevenueCat. Web and Android are live; iOS is not out yet.