What is the default Confluent Schema Registry compatibility type?

• A. None
• B. Forward
• C. Full
• D. Backward

Answer: (D)

Schema compatibility in Confluent Schema Registry determines how schemas can evolve without breaking readers or writers. The default setting is backward. This means that when you register a new version of a schema, it must be able to deserialize data written with the previous version, so newer readers can still read data produced by older schemas. In practice, adding an optional field with a default value preserves backward compatibility, because old data can be read by the new schema without issues. If you remove a field or change its type without a default, you would break backward compatibility. The other options describe different directions of compatibility (forward or full) or no guarantees, but the default is backward.