Kafka Broker Discovery and Zookeeper

Every Kafka broker is called a bootstrap server.
That means that you only need to connect to one broker and you will be connected to the entire cluster.
Each broker knows about all brokers, topics and partitions (metadata)

kafka broker_discovery

Zookeeper manages brokers (keeps a list of them)
Zookeeper helps in performing leader election for partitions
Zookeeper sends notifications to Kafka in case of changes (eg new topic, broker dies, broker comes up, delete topics etc)
Kakfa can't work without Zookeeper
Zookeeper by design operates with an odd number of servers(3, 5, 7)
Zookeeper has a leader (handle writes) the rest of the servers are followers (handle reads)
Zookeeper does NOT store consumer offsets with Kafka > v0.10)

kafka zookeeper