What does fetch.message.max.bytes configure?

• A. The maximum size of a message that can be replicated across brokers.
• B. The default maximum poll interval.
• C. The maximum size of message that can be fetched by a consumer from the broker.
• D. The default session timeout

Answer: (C)

Fetching in Kafka happens through fetch requests from a consumer to the broker. fetch.message.max.bytes sets a cap on how much data the broker will return in one of those fetch responses. In other words, it limits the total amount of message data that can be pulled in a single fetch, which helps control memory use on the broker and keep network traffic predictable. If a message batch would exceed this limit, the broker returns only the portion that fits, and the consumer may need additional fetches to get the rest. This setting is specifically about the data returned during fetch, not about replication, poll intervals, or session timeouts.