KNX Basic Exam Strategy

You know your material. This sheet earns you the 5-10 % of score that separates failure from a comfortable pass.

🎯 The rules of the game (reminder)

🧮 The maths of asymmetric scoring

Over N questions, with a correct / b wrong / c blank:

Score = a − 0.5 × b

with a + b + c = N.

Expected value of a pure random answer (T/F, 50 % chance):

E = 0.5 × (+1) + 0.5 × (−0.5) = +0.25 point

→ On a pure guess, the expected value is slightly POSITIVE.

The real threshold: 33 %, not 50 %

The expected value as a function of your confidence p is:

E(p) = p × (+1) + (1 − p) × (−0.5) = 1.5 p − 0.5

It reaches zero at p = 1/3 ≈ 33 %. As soon as you have better than a one-in-three chance of being right, answering beats leaving it blank.

⚠️ On a true/false item, "no idea" means 50 %, not 33 %: the expected value there is already +0.25. Dropping below 33 % on a binary item would mean you are wrong more often than chance — in which case the right move is to invert your hunch, not to abstain.

📋 Strategy in 3 rules

Rule 1 — If you are sure (>80 %), answer

Expected value = 0.8 × 1 + 0.2 × (−0.5) = +0.7 point. Always profitable.

Rule 2 — If you hesitate (50-80 %), answer

The expected value stays positive (from +0.25 to +0.70). Trust your course, re-read the question, check your PDF (open book), and answer.

Rule 3 — If you have no idea, answer anyway

On a true/false item, "no idea" means a 50 % chance, so an expected value of +0.25, against 0 for a blank. Abstaining only pays off below 33 % confidence, which cannot happen on a binary item.

Only leave blank what you had no time to read. Across 100 statements, abstaining five times costs you about 1.25 points.

⏱️ Time management (1 h 30 for 100 statements)

• Official pace: 54 s per statement. That is tight: review time is won on the obvious questions, not on the overall clock.
• First pass (50 min): answer all the obvious questions (Rule 1)
• Second pass (25 min): tackle the hesitations (Rule 2), consult the PDF
• Third pass (15 min): re-read the doubtful ones and answer any you left blank (Rule 3)
• Margin: never finish too early (a review is always profitable)

📚 Open book — using your documentation well

Before the exam

• Annotate your PDF with tabs or digital bookmarks
• Index the tricky topics: DPT, bus distances, address structure, scoring
• Print the essential CertifBus sheets (see CS-001 distances, CS-002 DPT) → you save 1-3 minutes of searching per question

During the exam

• Don't waste time looking for an info you won't find in 30 seconds: skip, mark the question, come back later
• Use the PDF to verify, not to learn. Check 2 figures, don't grasp 2 chapters
• The PDF contains the course material, not the full KNX Specs. Adjust your expectations accordingly

🚫 Classic traps in the KNX Basic exam

Trap 1 — The double negative

"It is not true that bus termination is useless" → careful analysis required. Read this kind of statement twice.

Trap 2 — Close numbers

350 m vs 700 m vs 1,000 m. The brain mixes them up under stress. Always verify in the doc/CS-001.

Trap 3 — DPT semantics

DPT 1.001 vs 1.008 vs 1.007 — all 1 bit. The trap is on the meaning not on the size. Check with CS-002.

Trap 4 — Topology area vs line

"15 lines per area" vs "15 areas per installation". The number is the same but the target is different. Re-read the question: what is it about?

Trap 5 — Open book doesn't mean "everything is in the PDF"

Some questions test logic (combinations of several rules) or practice (ETS workflow) that you can't "read" in the PDF. Prepare these topics in advance.

🧠 The day before the exam

• No cramming. Review the CertifBus sheets calmly.
• Sleep 7-8 h. Asymmetric scoring punishes fatigue (wrong hunches).
• Prepare your kit: PC provided by the centre, course PDF downloaded / printed, my.knx.org credentials ready.
• Eat light in the morning. Avoid the strong coffee that creates false confidence.

✅ Checklist 5 minutes before the exam

• my.knx.org credentials at hand
• Course PDF open and bookmarks ready
• Calculator if allowed by the centre (check)
• Water, tissues
• Phone switched off
• Calm breathing — you are ready

💡 Key takeaways

80 % confidence → answer. Hesitation → look up quickly, then answer. No idea → answer anyway. On a true/false exam scored +1 / −0.5 / 0, leaving a statement blank protects nothing: the expected value of a pure guess is positive. Only leave blank what you had no time to read.

Sources:

• KNX Support — Exam regulations
• KNX Support — Exam duration & passing score