Memory aids
Mnemonics that make it stick
Retention is a skill. These are the memory aids for the things you must recall under pressure — in exams, in interviews, on the job. Tap a card to reveal it.
The method
A · R · D
Absorption → Retention → Demonstration
Every task you do serves one of three jobs: get it in, make it stick, prove it. If a task fits none, question why you're doing it.
Cybersecurity
CIA triad
Confidentiality · Integrity · Availability
The three goals of all security. Ask of any control: which of the three does it protect — and what does it cost the other two?
Cybersecurity
AAA
Authentication · Authorization · Accounting
Who are you, what may you do, and what did you do. Most access-control questions map onto one of these three.
Cybersecurity
STRIDE
Spoofing · Tampering · Repudiation · Info disclosure · Denial of service · Elevation of privilege
A threat-modelling checklist. Walk a design against each letter to find where it can be attacked.
Networking
OSI layers
"Please Do Not Throw Sausage Pizza Away"
Physical, Data-link, Network, Transport, Session, Presentation, Application (layers 1→7). The sillier the sentence, the better it sticks.
Software
SOLID
Single-responsibility · Open/closed · Liskov · Interface-segregation · Dependency-inversion
The five principles of maintainable object-oriented design. Reach for it in code review and interviews.
Software
DRY / KISS / YAGNI
Don't Repeat Yourself · Keep It Simple · You Aren't Gonna Need It
Three habits that prevent most self-inflicted complexity. When stuck, ask which one you're violating.
Testing
Red · Green · Refactor
Fail first, pass minimally, then clean up
The test-driven-development loop. Write a failing test, make it pass simply, then improve the code with the test as a safety net.
Databases
ACID
Atomicity · Consistency · Isolation · Durability
The guarantees a transactional database gives. Contrast with BASE for eventually-consistent systems.
Debugging
R.I.F.V.
Reproduce · Isolate · Fix · Verify
A calm, repeatable method beats panic. Reproduce the bug, isolate the cause, change one thing, verify it's gone.
Estimating
Fermi first
Order-of-magnitude before precision
Break a scary number into pieces you can guess, multiply, and sanity-check. Right ballpark beats false precision.
