ccah-500 第46题 Which scenario will go undetected

46.You are running Hadoop cluster with all monitoring facilities properly configured.

Which scenario will go undetected?

A. HDFS is almost full

B. The NameNode goes down

C. A DataNode is disconnected from the cluster

D. Map or reduce tasks that are stuck in an infinite loop

E. MapReduce jobs are causing excessive memory swaps

Answer: B --> D

reference:

http://www.aiotestking.com/cloudera/which-scenario-will-go-undeselected/

 

B zookeeper monitors NameNode.
http://stackoverflow.com/questions/15642688/what-happens-when-name-node-fails-which-process-will-monitor-name-node-heart-be
此题注释不够充分，大家可以讨论下。