CCDAK Confluent Certified Developer for Apache Kafka Certification Examination Questions and Answers

SHOW STREAMS and EXPLAIN statements run against the KSQL server that the KSQL client is connected to. They don't communicate directly with Kafka. CREATE STREAM WITH and CREATE TABLE WITH write metadata to the KSQL command topic. Persistent queries based on CREATE STREAM AS SELECT and CREATE TABLE AS SELECT read and write to Kafka topics. Non-persistent queries based on SELECT that are stateless only read from Kafka topics, for example SELECT … FROM foo WHERE …. Non-persistent queries that are stateful read and write to Kafka, for example, COUNT and JOIN. The data in Kafka is deleted automatically when you terminate the query with CTRL-C.

Default port of KSQL server is 8088

Consumers do not directly write to the __consumer_offsets topic, they instead interact with a broker that has been elected to manage that topic, which is the Group Coordinator broker

You cannot have more sink tasks (= consumers) than the number of partitions, so 2.

The Schema Registry stores all the schemas in the _schemas Kafka topic

KSQL is not ANSI SQL compliant, for now there are no defined standards on streaming SQL languages

Both of these are retriable errors, others non-retriable errors. See the full list of errors and their "retriable" status herehttps://kafka.apache.org/protocol#protocol_error_codes

As of Kafka 2.3, the kafka-topics.sh command can take --bootstrap-server localhost:9092 as an argument. You could also use the (now deprecated) option of --zookeeper localhost:2181.

Mostly-static data is modeled as a table whereas business transactions should be modeled as a stream.

Since Confluent 5.4.0, Avro 1.9.1 is used. Since default value was added to enum complex type , the schema resolution changed from:

(<1.9.1) if both are enums:** if the writer's symbol is not present in the reader's enum, then an error is signalled. **(>=1.9.1) if both are enums:

if the writer's symbol is not present in the reader's enum and the reader has a default value, then that value is used, otherwise an error is signalled.

GlobalKTables have their datasets replicated on each Kafka Streams instance and therefore no repartitioning is required

TLS - but it is still called SSL.

Each broker must have a unique broker id and connect to the same zk ensemble and root zNode

These are the client side exceptions that may be encountered before message is sent to the broker, and before a future is returned by the .send() method.

auto.offset.reset=none means that the consumer will crash if the offsets it's recovering from have been deleted from Kafka, which is the case here, as 10 < 45

Replicas are passive - they don't handle produce or consume request. Produce and consume requests get sent to the node hosting partition leader.

This is active-passing as the replicated topic is used for read-only purposes only

Kafka transfers data with zero copy and no transformation. Any transformation (including compression) is the responsibility of clients.

In case the consumer has the wrong leader of a partition, it will issue a metadata request. The Metadata request can be handled by any node, so clients know afterwards which broker are the designated leader for the topic partitions. Produce and consume requests can only be sent to the node hosting partition leader.