10 MongoDB Interview Questions Every Backend Developer Should Know

I still remember my first backend interview.

Everything was going smoothly.

Node.js?
APIs?
Authentication?

Then the interviewer asked:

“How does MongoDB handle relationships?”

I paused.

Not because I didn’t use MongoDB.

But because I had never really understood it deeply.

That day taught me something important:

Using a database is easy. Understanding it is what gets you hired.
If you’re preparing for backend roles in 2026, these MongoDB questions can make a real difference.

1. What Is MongoDB?

MongoDB is a NoSQL database that stores data in JSON-like documents instead of tables.

Instead of rows and columns, you work with:

• Collections (like tables)
• Documents (like rows, but flexible)

Example document:

1. What Is MongoDB?

MongoDB is a NoSQL database that stores data in JSON-like documents instead of tables.

Instead of rows and columns, you work with…