What is active and passive NameNode in Hadoop?

501

Is it possible to have hadoop job output in multiple directories? If yes, how?

490

What is pseudo-distributed mode?

646

What do you think about the speculative execution?

479

What are the four modules that make up the Apache Hadoop framework?

593

What are input format, input split & record reader and what they do?

663

What happen if a datanode loses network connection for a few minutes?

643

Is nosql follow relational db model?

502

What are the differences between hadoop 1 and hadoop 2?

468

Why aggregation cannot be done in Mapper?

607

What kind of hardware is best for hadoop?

463

What are the major differences between Hadoop 2 and Hadoop 3?

521

What do you understand by standalone (or local) mode?

473

Can you define udf?

475

What is difference between secondary namenode, checkpoint namenode & backupnode?

503