Most candidates recite the Adam update equation and stop. The interviewer wants the decision: when plain SGD with momentum still wins, why Adam is the safe default for new architectures, and how you diagnose a training run that is silently dying from a gradient that shrank to zero.
Walk me through SGD vs mini-batch vs Adam, learning-rate schedules, and what vanishing or exploding gradients look like in practice.
Most candidates recite the Adam update equation and stop. The interviewer wants the decision: when plain SGD with momentum still wins, why Adam is the safe default for new architectures, and how you diagnose a training run that is silently dying from a gradient that shrank to zero.
Updated Sep 2026 · Grounded in real Forward Deployed Engineer interview loops and written to a senior-engineer editorial bar.
The screen is whether you treat the optimizer as a diagnostic instrument rather than a formula to memorize. The reserved follow-up is almost always 'how would you tell vanishing from exploding gradients from the logs alone' and 'why does Adam sometimes generalize worse than SGD'. Naming the gradient-norm trace and the SGD-generalizes-better finding before being asked is the senior signal.
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