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AI Infra Interviews

Prepare for
AI infrastructure
interviews.

Work through the numbers behind GPU systems, from a single model to a training cluster. Learn to explain your decisions and handle the follow-up.

130 answers to read now · 260 with a free account · no card

A question to start with

How much memory does your model need?

Change the model or context. Watch the memory budget change.

Live · will it fit?
full calculator →
Hardware
KV per token
328 KB
Per sequence
10.7 GB
8 × H100 80GB SXM · 640 GB
40 sequences fit the memory budget at 32k, after 141 GB of weights and 10% reserved

KV/token = 2 × 80 layers × 8 KV heads × 128 × 2 B

Memory estimate only. Actual serving capacity depends on parallel layout, runtime overhead and latency targets.

GPU LAB / HANDS-ON GPU COMMAND EMULATOR

A terminal. A GPU cluster.
Your next investigation.

Run inference and training workloads. Watch memory fill, follow live GPU graphs, then investigate a broken link or a service that refuses to start. Practice NVIDIA commands in your browser, with guided missions from your first terminal session to cluster recovery.

3 free missions · 21 Premium missions · no hardware to rent

GPU-01 / B200INTERACTIVE PREVIEW

Change the workload. Read the machine.

Your first GPU is one click away.

Run a workload on GPU 0. Follow its activity and memory, pause the clock, then switch workloads to compare.

01 ActivityIs the GPU busy?02 MemoryWhat stays allocated?03 ProcessesWho owns the work?04 RecoveryWhat changes after a fault?
learner@gpu-01:~ $ nvidia-smi -i 0

No account or GPU required. Starts only when you press Run.

24 guided missions6 learning chapters8 × 8 nodes × GPUs in the sandbox4 GPU architecture profiles
Learn it. Diagnose it. Try again.

A free eight-node sandbox, guided explanations, challenges with help hidden, a command reference and a personal review queue.

Browser-based GPU command emulation. CUDA execution and hardware performance testing require real GPUs.

Interactive explainer · runs in your browser

Watch a real model serve your prompt

Follow one prompt through tokens, prefill, the KV cache, decode and sampling. Every number on the page comes from a real model running the request: the time each step takes, the bytes it reads and the memory it keeps.

  • Tokens
  • Prefill
  • KV cache
  • Decode
  • Sampling
  • Production scale

Free to explore; the production-scale stage is Premium. No account or GPU needed.

Your prompt, as the model sees it
To2068·make919·a253·cup7118·of282·tea7188,28·first808·boil17663·the260·water913
Measured cost per token
Prefill
5.6 ms
Decode
23.0 ms
Decode costs 4.1× more per token: every decode pass reads all 135 million weights to make one token. Recorded with the same 8-bit model the explainer runs.
New to AI infrastructure?

Start with one request.
Build from there.

Learn what the machine does, what the model stores, and why an answer can be slow. Then try a memory budget and choose your first lesson.

Start learning the basics →

Five steps · free to read · no account or GPU needed

  1. CPU, GPU and memory
  2. Models, weights and precision
  3. A prompt becomes output tokens
  4. Your first memory budget
  5. Inference, training or GPU programming

Build it step by step

Hands-on guides

Train a tiny model, compare fine-tuned adapters, or configure and tune a private model service. Follow the commands and inspect what each step produces.

Explore all 20 guides →

See how we teach

Follow the arrows.
Understand the system.

What happens between your prompt and the next token? Follow the loop in this diagram from our inference platform walkthrough.

Start with the picture. The full answer connects it to the request path, works through a capacity example, and explains what to check when a request stalls.
Read the full walkthrough →

Free to read · no account needed

Inside the generation loop Consume model inputPrompt, then latest token Embedding → layersAttention reads past KV.Layers add state forthe consumed positions. Scores → next tokenApply decoding policy.Continue: feed it back. Stop Finish this requestKeep or release idle KV. Consume A, B → emit C.KV covers A and B, not C yet. Consume C → emit D.Now KV includes C.
From the question bankWalk me through an inference platform for a hosted LLM. What are the pieces, and what does each one do?

Open the answer. Check the reasoning.

Start with a question you should know.

Find your starting point →

Keep the questions you want to come back to.

A free account gives you 260 answers, bookmarks and saved progress.

Join free →

Prepare for the work you want to do

Which interview are you preparing for?

New to AI infra? Start here →

Build the foundations

Prefer a course
to a question bank?

Follow the lessons in order, then put the ideas to work.

Explore all 7 courses →

Go deeper when you’re ready

Make room for
the hard questions.

Work through the full bank, study the underlying concepts, and follow a course from the foundations into system design.

One payment. 6 months of access. No auto-renewal.

Full access

$25 USD / ₹2,000 INR
  • All 448 worked answers, including hard and expert questions
  • The full 179-concept library and all 7 courses
  • Premium practice modes, bookmarks and progress tracking
Get full access →

Start with a free account and decide after you’ve studied.

Focus your preparation

Learn what your target company emphasizes.

All 47 company guides →

Explore reported interview formats and relevant topics. Each guide distinguishes documented details from limited public evidence. Loops vary by team; confirm yours with the recruiter.

Independent preparation. No affiliation with or endorsement by the companies named.

AI INFRA CAREERS · FREE

Find the team you want to build with.

Explore GPU, training, inference and platform openings at companies we track. Filter by specialty and location, then prepare for that company.

Browse AI infra jobs

Guides & handbooks

Go deeper, one guide at a time.

Browse all 15 guides →

Our nine latest guides, from a first model request to the systems behind a production fleet. Explore the contents and sample pages before choosing your next read. Complete Premium guides require paid or approved access.

PAID REMOTE INTERNSHIP

Help your campus learn about AI.

Contribute useful content and bring students together while learning about the infrastructure behind AI. Join us as a Community & Campus Intern.

Fully remote US$25 per week Outcome-based

Learn here. Help someone else start.

Good resources travel through good people.

Know someone learning AI infrastructure? Share a useful resource on both LinkedIn and X and apply to become a Community Ambassador.

Explore the ambassador program →
Community Ambassador

Recognition for helping others learn.

After team approval: a gold badge beside your comments and a one-time 48-hour Premium pass. Already Premium? Earn the badge and save the pass.

01 Share02 Submit proof03 Team review

Keep exploring

The AI infrastructure library.

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