High CI/CD Question 196 of 226

What is your rollback strategy when a MERN release is bad?

MERN Full Stack · Speak this in 60–90 seconds · Faridabad & Delhi NCR

PICTURE THIS: DATABASE INDEX

Without indexScan every row
With indexJump to keys
CostWrites slower

Simple meaning

Redeploy the previous known-good artifact rather than hotfixing forward under pressure.

1

WHY — CI/CD instead of guessing?

Why interviewers care about CI/CD:

CI/CD questions separate people

who only read docs from people who shipped.

Keep it short, concrete,

and tied to Full Stack work.

Stay structured

Name the idea, why it exists, then one short example.

Close cleanly

End with when you use it and one common pitfall.

2

STEPS — What happens step by step?

Before you speak the answer, walk the interviewer through these steps:

  1. 1
    Redeploy the previous known-good

    artifact rather than hotfixing forward under pressure.

  2. 2
    Database migrations must be

    backward compatible so the old API can still run.

  3. 3
    Feature flags let you

    disable a path without a full rollback when the migration cannot reverse easily.

  4. 4
    Give an example

    One tiny concrete case you can say aloud.

  5. 5
    Common mistake

    What juniors usually get wrong.

  6. 6
    Close

    When you pick this over the alternative.

3

EXAMPLE — See it in action

Here's a short line you can speak, broken into clear beats:

Say this line
“Database migrations must be backward compatible so the old API can still run.”
Break into beats
Databasemigrationsmustbebackwardcompatible
Speaking order
2987408337471632900

Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.

Key takeaway

Redeploy the previous known-good artifact rather than hotfixing forward under pressure. Database migrations must be backward compatible so the old API can still run.

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