It's all about the Hadoop and YARN setup and configurations and commanding over Hadoop and YARN. Here are some web interfaces used by Hadoop and YARN administrators for admin tasks:

The URL for the NameNode is http://<namenode_host>:<port>/ and the default HTTP port is 50070.

The URL for the ResourceManager is http://<resourcermanager_host>:<port>/ and the default HTTP port is 8088. TheWeb UI for the NameNode can be seen as follows:

The URL for the MapReduce JobHistory Server is http://<jobhistoryserver_host>:<port>/ and the default HTTP port is 19888.