What is nesting — CCA-F Exam Prep

5 days until launch. The deployment config is 4 levels deep.
A database setting nested inside a services block, inside an environment block, inside the root config. The junior dev needs to change one number: database timeout from 30 seconds to 60.
They find "timeout: 30" and change it to 60. But there are three different "timeout" keys in the file -- at different levels. They changed the API gateway timeout, not the database timeout.