Common interview mistakes
The mistakes that sink otherwise strong candidates: designing before asking, unit errors in estimates, buzzword architecture, ignoring failures, and going silent.
20 min6 steps
By the end you can
- Catch the unit and time-base errors that inflate or deflate estimates
- Recognise premature detail and buzzword architecture, and replace them with reasoned components
- Raise failure modes and operational concerns without waiting to be asked
- Keep the interviewer in the loop by thinking aloud and checking in at stage boundaries
Designing before understanding
Draw in minute one
- Commits before read/write ratio, consistency, scale
- Defending boxes
Understand first
- Requirements, then numbers
- Design follows reasoning
Unit errors in estimates
Seconds per day
86,400
not 3,600
Bits vs bytes
x8
Forgotten
replication, peak factor
Effect
3x to 24x off
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Buzzword architecture
Say instead
- What it decouples
- What ordering it gives
- What happens when consumers lag
Red flag
- Technology name with no reason
Forgetting that things fail
Going silent
Requirements
Summarise: these needs
Numbers
These estimates
Design
Ask: go deeper or move on?
Check your mastery, then run a mock
Look for
each mistake in your own session
Score 80% or more. Run a full mock in interview mode, then score against the rubric.
Mastery check
3 questions on fresh variants. One attempt each, no time limit. Score 80% or more to master the lesson.
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