Retry Strategies and Poison Pills

Not all errors are the same. Transient errors (network timeout, temporary database lock) should be retried. Permanent errors (malformed schema, null in a NOT NULL field) will never succeed no matter how many times you retry. The interview tests whether you can classify errors and route them differently. Retry Queue vs Dead Letter Queue Poison Pill Detection A poison pill is a message that causes the consumer to crash every time it tries to process it. Without detection, the consumer enters a crash loop: read poison pill, crash, restart, read same poison pill, crash again. The pipeline is stuck.