The 6-week fundamentals drill

This is the drill half of the fundamentals track. One subject per week, six weeks, using the KnowledgeGate question bank as the source.

The format is the method. Each week ends with one test: can you answer every question below out loud, recorded, in 60 to 90 seconds each? Silent reading does not count, because the interview is spoken.

Record on your phone, listen once, note where you stalled, and move on. Do not script the answers.

Week 1: operating systemsCopy Anchor Link

You should be able to answer:

• Name the four Coffman conditions for deadlock, and say how to break each one.
• Run FCFS, SJF and round robin over the same three jobs by hand, and compare the waiting times.
• Explain why SJF lowers average wait, and why scheduling it needs a prediction.
• Walk one page fault end to end: page table lookup, the miss, then LRU eviction.
• Say the difference between a process and a thread, with one example of what they share.
• Say when a mutex is the right tool and when a semaphore is.

Why it matters: deadlock and scheduling are the cheapest questions an interviewer can ask, and a hesitant answer sets the tone for the rest of the round.

Week 2: DBMSCopy Anchor Link

You should be able to answer:

• Normalise a deliberately broken table from 1NF to 3NF, and name what breaks at each step.
• Give ACID with one concrete failure per letter.
• Write inner, left and right joins on the same two tables, and pivot the result by hand.
• Explain an index as a B-tree lookup, and say when it hurts writes.
• Walk EXPLAIN ANALYZE on one of your own queries and point at the expensive node.

Why it matters: this is the week where your answers can come from your own database instead of a tutorial table.

Week 3: networksCopy Anchor Link

You should be able to answer:

• Defend TCP over UDP for payments, then name one case where UDP wins.
• Draw the three way handshake and say what each packet carries.
• List what the TLS 1.3 handshake exchanges, and what it does not.
• Compare HTTP 1.1 and HTTP 2, and explain what multiplexing fixes.
• Answer "what happens when you type a URL" in 90 seconds: DNS, then TCP, then TLS, then HTTP.

Why it matters: network questions appear in almost every backend loop, and they are easy to answer badly in broad strokes.

Week 4: OOP and LLD warm-upCopy Anchor Link

You should be able to answer:

• State the four pillars in one sentence each, with an example from code you wrote.
• Explain SOLID, and name one violation you have personally shipped.
• Choose composition or inheritance for a case, and defend the choice.
• Sketch the classes for a small system without writing code.

Why it matters: this is the bridge into the LLD track, and it is the vocabulary the design round assumes you already have.

Week 5: concurrency in GoCopy Anchor Link

You should be able to answer:

• Explain goroutine vs thread, channels, select, context cancellation, data race and mutex, in that order and out loud.
• Write 3 tiny programs: fan-out and fan-in, a worker pool with graceful shutdown, and a rate-limited HTTP client.

Why it matters: job descriptions test concurrency, and it feeds directly into the Logsmith build, where consumer groups are a concurrency exercise.

Week 6: databases IICopy Anchor Link

You should be able to answer:

• Name read committed and serializable, and the anomaly each one prevents.
• Compare optimistic and pessimistic locking, with one example each.
• Explain connection pooling, and describe what an exhausted pool looks like.
• Spot an N+1 query in a code path and say how you would fix it.

Why it matters: most backend rounds end on a database question, and this is where points are lost quietly.

After the six weeksCopy Anchor Link

Re-answer the whole set once a month from January. Keep the recordings, because the difference between the week 1 and week 8 answer of the same question is the progress you cannot otherwise see.