A ZooKeeper Quorum consisting of three ZooKeeper servers has been created.

The zoo.cfg located on all three ZooKeeper servers looks as follows:

# The number of milliseconds of each tick
# The number of ticks that the initial
# synchronization phase can take
# The number of ticks that can pass between
# sending a request and getting an acknowledgement
# the directory where the snapshot is stored.
# the port at which the clients will connect



It is clear that one of the three ZooKeeper servers will become the Leader and the others Followers. If the Leader ZooKeeper server has been shutdown, the Leader election will start again. The aim is to check if another ZooKeeper server will become the Leader if the Leader server has been shut down.


It is possible to check whether a ZooKeeper server is a leader or follower using the nc command that is included in the netcat package:

echo stat | nc localhost 2181 | grep Mode
echo srvr | nc localhost 2181 | grep Mode #(From 3.3.0 onwards)

If the ZooKeeper server is a leader then the command will return: Mode: leader and otherwise: Mode: follower

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  • 2
    and standalone – zinking Jan 4 '16 at 9:23
  • @bsd , is there any way to find the nodes in zookeeper cluster ?? – Sumit Murari Sep 6 '16 at 6:10
  • 2
    @sumit That probably needs its own SO question, but one way is to simply read the zoo.cfg file. – Jose Leon Dec 9 '16 at 14:33

Alternatively the following could be used:

bin/zkServer.sh status

It will print the mode in the output:

ZooKeeper JMX enabled by default
Using config: /home/kafka/zookeeper/bin/../conf/zoo.cfg
Mode: follower
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