Task 3: Use Data Stores in Application Development DVA-C02 Practice Questions (Page 2)

Questions 6–10

1. 6application · medium

   A developer is storing user preferences in Amazon ElastiCache for Redis. The preferences include a username, a list of favorite genres, and a boolean flag for email notifications. The developer needs to store this as a single Redis value. Which serialization format is the most appropriate for this use case?

   • AXML using a DOM parser.
   • BCSV with comma-separated values.
   • CJSON using `JSON.stringify()` and `JSON.parse()`.
   • DJava serialization using `ObjectOutputStream`.
   Reveal Solution Discussion Select an answer first
2. 7foundation · easy

   What is the primary difference between a DynamoDB Query and a Scan operation?

   • AQuery retrieves items based on primary key values, while Scan examines every item in the table
   • BQuery retrieves all items in the table, while Scan filters by primary key
   • CQuery is used for eventually consistent reads, while Scan is used for strongly consistent reads
   • DQuery can only be used on tables with a sort key, while Scan can be used on any table
   Reveal Solution Discussion Select an answer first
4. 8foundation · easy

   Which statement correctly describes the difference between strongly consistent and eventually consistent reads in DynamoDB?

   • AEventually consistent reads always return the most recent write, while strongly consistent reads might return stale data
   • BStrongly consistent reads always return the most recent write, while eventually consistent reads might return stale data
   • CStrongly consistent reads are faster and cheaper than eventually consistent reads
   • DEventually consistent reads require a sort key, while strongly consistent reads do not
   Reveal Solution Discussion Select an answer first
5. 9foundation · easy

   A developer is designing a DynamoDB table to store IoT sensor readings. Which partition key choice would best distribute writes evenly across partitions?

   • AThe sensor type, which has only a few possible values
   • BThe device ID, which has thousands of unique values
   • CA composite key of device ID plus timestamp
   • DThe timestamp of the reading, rounded to the nearest hour
   Reveal Solution Discussion Select an answer first
6. 10foundation · easy

   Which caching strategy involves checking the cache first and, on a miss, loading the data from the database and then storing it in the cache?

   • ACache-aside
   • BWrite-through
   • CWrite-behind
   • DRead-through
   Reveal Solution Discussion Select an answer first