This set of Hadoop Multiple Choice Questions and Answers focuses on “The ZooKeeper Service – 2”.
1. You need to have _________ installed before running ZooKeeper.
a) Java
b) C
c) C++
d) SQLGUI
View Answer
Explanation: Client bindings are available in several other languages.
2. Point out the correct statement.
a) All znodes are ephemeral, which means they are describing a “temporary” state
b) /hbase/replication/state contains the list of RegionServers in the main cluster
c) Offline snapshots are coordinated by the Master using ZooKeeper to communicate with the RegionServers using a two-phase-commit-like transaction
d) None of the mentioned
View Answer
Explanation: Although the Replication znodes do not describe a temporary state, they are meant to be the source of truth for the replication state, describing the replication state of each machine.
3. How many types of special znodes are present in Zookeeper?
a) 1
b) 2
c) 3
d) All of the mentioned
View Answer
Explanation: There are two special types of znode: sequential and ephemeral.
4. To register a “watch” on a znode data, you need to use the _______ commands to access the current content or metadata.
a) stat
b) put
c) receive
d) gets
View Answer
Explanation: ZooKeeper can also notify you of changes in a znode content or changes in a znode children.
5. Point out the wrong statement.
a) All the znodes are prefixed using the default /hbase location
b) ZooKeeper provides an interactive shell that allows you to explore the ZooKeeper state
c) The znodes that you’ll most often see are the ones that coordinate operations like Region Assignment
d) All of the mentioned
View Answer
Explanation: The HBase root znode path is configurable using hbase-site.xml, and by default the location is “/hbase”.
6. _______ has a design policy of using ZooKeeper only for transient data.
a) Hive
b) Imphala
c) Hbase
d) Oozie
View Answer
Explanation: If the HBase ZooKeeper data is removed, only the transient operations are affected – data can continue to be written and read to/from HBase.
7. Zookeeper keep track of the cluster state such as the ______ table location.
a) DOMAIN
b) NODE
c) ROOT
d) All of the mentioned
View Answer
Explanation: Zookeeper keeps track of list of online RegionServers, unassigned Regions.
8. The ________ master will register its own address in this znode at startup, making this znode the source of truth for identifying which server is the Master.
a) active
b) passive
c) region
d) all of the mentioned
View Answer
Explanation: Each inactive Master will register itself as backup Master by creating a sub-znode.
9. ___________ is used to decommission more than one RegionServer at a time by creating sub-znodes.
a) /hbase/master
b) /hbase/draining
c) /hbase/passive
d) None of the mentioned
View Answer
Explanation: /hbase/draining lets you decommission multiple RegionServers without having the risk of regions temporarily moved to a RegionServer that will be decommissioned later.
10. The ______ znode is used for synchronizing the changes made to the _acl_ table by the grant/revoke commands.
a) zcl
b) acl
c) scl
d) bnl
View Answer
Explanation: Each table will have a sub-znode (/hbase/acl/tableName) containing the ACLs of the table.
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