What is the difference between immutable and mutable infrastructure?

• A. Immutable replaces components for changes; mutable patches existing ones
• B. Immutable patches existing components; mutable replaces them
• C. They are the same concept
• D. Mutable never changes once deployed

Answer: (A)

The key distinction is how you apply changes to infrastructure. In immutable infrastructure, you don’t modify a running resource. instead you create a new resource with the desired changes (a new VM or container image with the updated software or configuration), deploy it, and switch traffic to the new resource while the old one is gradually decommissioned. This approach makes it easy to roll back by simply reactivating a previously released version.

That idea is why the correct option is the one that says changes are achieved by replacing components rather than patching them in place. Patching or updating an existing component describes mutable infrastructure, where in-place changes are made to the current resource. They’re not the same concept, and mutable does involve changes after deployment, not a guarantee that nothing ever changes.