Which of the following binaries handles routing of sharded queries to the proper shard?

MongoDB document names cannot start with the characters:

What is the extra space allocated to document on the disk to prevent moving a document when it grows as the result of update() operations.

What do drivers use with protocol on the wire?

Due to their default behavior, Capped Collections are ideal for storing:

When a Capped Collection becomes full, and a new document is added:

How often do the members of a replica set send heartbeats to each other?

Why are ad-hoc queries useful?

A compound index allows you to _ ?

One of the documents in your collection has an _id based upon an older database design and you want to change it. You write an update command to find the document and replace the _id but the _id isn't changed. How should you fix the issue?

Assuming you have customers collection with a firstName and lastName field, which is the correct MongoDB shell command to create an index on lastName, then firstName both ascending?