Cloudera Cloudera Certifications CCB-400 Questions & Answers

• Question 31:

  You have 40 Web servers producing timeseries data from Web traffic logs. You want to attain high write throughput for storing this data in an HBase table. Which of these should you choose for a row key to maximize your write throughput?

  A.

  B. ;

  C.

  D.

  Correct Answer: C

• Question 32:

  Your client application if; writing data to a Region. By default, where is the data saved first?

  A. StoreFile

  B. WAL

  C. MemStore

  D. Local disk on theRegionServer

  Correct Answer: C

  Reference:http://www.cloudera.com/blog/2012/07/hbase-log-splitting/(Log splitting, first paragraph)

• Question 33:

  You want to do a full table scan on your data. You decide to disable block caching to see if this improves scan performance. Will disabling block caching improve scan performance?

  A. No. Disabling block caching does notimprove scan performance.

  B. Yes.When you disable blockcaching, youfreeup that memory for other operations.Witha full table scan,you cannot take advantage of blockcaching anyway because your entiretable won'tfitinto cache.

  C. No. If you disable block caching, HBase must read each block index from disk for each scan,thereby decreasing scan performance.

  D. Yes. When you disable block caching, youfree up memory forMemStore, which improves,scanperformance.

  Correct Answer: B

• Question 34:

  Your client application needs to scan s region for the row key value 104.

  Given a store that contains the following list of Row Key values:

  100, 101, 102, 103, 104, 105, 106, 107

  A bloom filter would return which of the following?

  A. Confirmation that 104 may becontained in theset

  B. Confirmation that 104 is contained in the set

  C. Thehash of column family

  D. The file offset of the value 104

  Correct Answer: B

• Question 35:

  Which feature of HBase ensures predictable disk head seek performance within a RegionServer?

  A. Data is stored distributed in HDFS

  B. Data stored in HBase is sparse

  C. Data is stored sorted on row keys

  D. Data is stored as an uninterpreted array of bytes

  Correct Answer: C

• Question 36:

  Given that following is your entire dataset:

  100 column=Managers:Name, timestamp=13313141762084, value=Steve 100 column=Manage:Salary, timestamp=13313141762086, value=80000 100 column=Skills:Skill_1, timestamp=13313141762089, value=Hadoop 100 column=Skills:Skill_2, timestamp=13313141762092, value=HBase How many sets of physical files will be read during a scan of the entire dataset immediately following a major compaction?

  A. Two

  B. One

  C. Three

  D. Four

  Correct Answer: B

• Question 37:

  You need to create a "WebLogs" table in HBase. The table will consist of a single Column Family called "Errors" and two column qualifiers, "IP" and "URL". The shell command you should use to create the table is:

  A. create'WebLogs',{NAME =>'Errors:IP', NAME =>'Errors:URL'}

  B. create'WebLogs','Errors'{NAME =>'IP', NAME =>'URL'}

  C. create'WebLogs','Errors:IP','Errors:URL'

  D. create'WebLogs','Errors'

  Correct Answer: C

• Question 38:

  You have a table with the following rowkeys:

  r1, r2, r3, r10, r15, r20, r25, r30, r35

  In which order will these rows be retrieved from a scan?

  A. r35,r30,r3,r25,r20,r2,r15,r10,r1

  B. r1,r2,r3,r10,r15,r20, r25,r30,r35

  C. r1,r10,r15,r2,r20,r25,r3,r30,r35

  D. r35,r30,r25,r20,r15,r10,r3,r2,r1

  Correct Answer: D

• Question 39:

  Data is written to the HLog in which of the following orders?

  A. In order of writes

  B. In order of writes, separated by region

  C. Ascending first by region and second by row key

  D. Descending first by region and second by row key

  Correct Answer: D

• Question 40:

  You have two standbys and one primary HMaster. Your primary HMaster fails. Which of the remaining HMasters becomes the new primary?

  A. Whichever HMaster first responds to ZooKeeper

  B. Whichever HMasterZooKeeper randomly selects

  C. Whichever HMastercreates the znode first

  D. Whichever HMaster has the lower IP address

  Correct Answer: A