1. Motor Plants (Q620)
Key exam domainIdentify weak areas and improve with focused review.
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Free DDE Practice Test
Pass the National Designated Duty Engineer Steam/Motor/GT (DDE) exam with confidence.
Start with a free DDE practice test and build exam-ready confidence for the National Designated Duty Engineer Steam/Motor/GT (DDE) exam.
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1000+DDE Questions
6Exam Domains
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2026Updated
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Everything your DDE certification prep needs
Practice expert-vetted questions, find your weak domains, and turn every mistake into a focused review plan.
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Practice the DDE exam by domain
2. Steam Plants (Q621)
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing3. Gas Turbine Plants (Q622)
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing4. Engineering Safety & Environmental Protection (Q623)
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing5. General Subjects (Q624)
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing6. Electricity, Electronics & Control Engineering (Q625)
Key exam domainIdentify weak areas and improve with focused review.
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Frequently asked questions
Straight answers about the DDE exam, the questions, pricing, the free trial, and how this fits your prep.
The DDE exam spans 6 domains - Motor Plants (Q620), Steam Plants (Q621), Gas Turbine Plants (Q622), Engineering Safety & Environmental Protection (Q623), General Subjects (Q624), and Electricity, Electronics & Control Engineering (Q625). Every practice question maps to one of them, so you train on exactly what's tested.
No - and that matters. These are original practice questions written to mirror the style, difficulty, and domain coverage of the DDE exam blueprint. We never distribute actual exam content, so practicing here keeps you fully compliant with official exam policies.
No. DDE Exam Prep is an independent study resource for National Designated Duty Engineer Steam/Motor/GT (DDE). It is not affiliated with, sponsored by, or endorsed by the official certifying body or exam administrator.
Every paid plan unlocks the full bank of 1,000+ practice questions covering all 6 DDE domains - Motor Plants (Q620), Steam Plants (Q621), Gas Turbine Plants (Q622), Engineering Safety & Environmental Protection (Q623), General Subjects (Q624), and Electricity, Electronics & Control Engineering (Q625). You can practice the whole bank, filter by domain, or run a timed, domain-balanced exam simulation.
Yes - the bank is maintained against the current exam outline, and questions are revised when the exam changes.
No honest practice platform can guarantee a pass. What realistic practice does is show you - before exam day - exactly which domains are weak, and give you the repetitions to fix them. That's the difference between hoping you're ready and knowing where you stand.
Yes. You get 10 free sample questions with instant feedback - no credit card and no account required.
The free sample shows you the question quality. Paid plans unlock the full 1,000+ question bank, exam-style practice modes, mistake review, and - on Fast Track and Pass Confidence - progress analytics that show your readiness by domain.
No. Every plan is a single one-time payment for a fixed access window - 48 hours, 7 days, or 6 weeks. There is no auto-renewal and no recurring billing.
Match it to your exam date: Final Review (2 days) for an exam in the next day or two, Fast Track (7 days) for an exam this week, Pass Confidence (6 weeks) for a structured run-up.
For most countries, the price you see is exactly what you pay - tax is already included. Where local law requires it to be added separately, it's shown clearly at checkout before you pay, so there are never any surprise fees.
Access is instant after payment and runs for your plan's full window from that moment. When the window ends, your local progress stays on your device - you can buy another window any time and pick up where you left off.
Yes - the whole platform is mobile-first: practice, mistake review, and analytics all work on any phone, tablet, or laptop with a browser. Nothing to install.
Every answer feeds your per-domain accuracy, readiness score, and weak-area list. Instead of re-reading everything, you drill the domains that are actually costing you points - that's what moves a score in days, not months.
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Trusted by DDE candidates
Real feedback from DDE candidates on Reddit.
"passed last month. honestly didnt study near enough until the last two weeks. the practice questions on fuel injection and starting systems saved me, kept missing the same stuff until i drilled it over and over. wouldnt have caught that otherwise."
"put this off for months, kept telling myself id start studying next week. finally sat down and the mistake review thing actually showed me i kept blowing governor and casualty control questions. went back thru those sections specifically and it clicked eventually. no fireworks, just relief when the results came back."
"used ddeexam.com for about a month before my exam, mostly did the full length mocks on weekends. the electrical troubleshooting section was my weak spot and seeing where i stood before test day helped alot. passed first try, still kinda surprised tbh."