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Akanksha
Akanksha

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Top 30 Redis Interview Questions with Answers

1. What is Redis?

a. A relational database management system
b. An in-memory data structure store
c. A document-oriented database
d. A distributed file system
Answer: b. An in-memory data structure store

2. Which programming languages can be used to interact with Redis?

a. Only Python
b. Only Java
c. Multiple programming languages
d. Only C++
Answer: c. Multiple programming languages

3. What data structures does Redis support?

a. Arrays, Linked Lists, and Sets
b. Dictionaries, Arrays, and Strings
c. Stacks, Trees, and Graphs
d. Lists, Sets, and Sorted Sets
Answer: d. Lists, Sets, and Sorted Sets

4. Which of the following is a valid use case for Redis?

a. Storing large multimedia files
b. Session caching
c. Long-term data storage
d. Complex queries
Answer: b. Session caching

5. What is the maximum size of a value that Redis can handle?

a. 1 MB
b. 5 MB
c. 10 MB
d. 512 MB
Answer: d. 512 MB

6. How is data replication achieved in Redis?

a. Through clustering
b. Through sharding
c. Through replication using master-slave configuration
d. Through partitioning
Answer: c. Through replication using master-slave configuration

7. Which Redis command is used to set the value of a key?

a. SET
b. GET
c. PUT
d. UPDATE
Answer: a. SET

8. What is a Redis sentinel?

a. A Redis data structure
b. A tool for monitoring Redis instances
c. A Redis data type
d. A Redis configuration file
Answer: b. A tool for monitoring Redis instances

9. Which data type in Redis is used to store an ordered collection of elements?

a. List
b. Set
c. Hash
d. Sorted Set
Answer: d. Sorted Set

10. What is the default port for Redis server?

a. 6379
b. 5432
c. 3306
d. 27017
Answer: a. 6379

11. Which Redis command is used to increment the value of a key?

a. INCR
b. INC
c. INCREMENT
d. ADD
Answer: a. INCR

12. What is the main advantage of using Redis?

a. High availability
b. Durability of data
c. In-memory data storage for quick access
d. Complex querying capabilities
Answer: c. In-memory data storage for quick access

13. Which data type in Redis is an unordered collection of unique elements?

a. Set
b. List
c. Hash
d. Sorted Set
Answer: a. Set

14. What is the purpose of a Redis hash data type?

a. Storing strings with unique keys
b. Storing lists of elements
c. Storing an unordered collection of unique elements
d. Storing a map between field and value
Answer: d. Storing a map between field and value

15. Which Redis command is used to retrieve multiple values for given keys?

a. MGET
b. MSET
c. GETALL
d. GETMULTI
Answer: a. MGET

16. Which Redis data type is best suited for representing a social media feed where posts need to be sorted by time?

a. Set
b. Sorted Set
c. Hash
d. List
Answer: b. Sorted Set

17. What is Redis pipelining?

a. A technique to improve network latency
b. A way to partition data across multiple servers
c. A method for encrypting data in transit
d. A Redis data type
Answer: a. A technique to improve network latency

18. Which Redis command is used to remove and get the first element in a list, or block until one becomes available?

a. LPOP
b. RPOP
c. POP
d. GET
Answer: a. LPOP

19. What is the TTL (Time to Live) for a key in Redis by default?

a. 1 hour
b. 24 hours
c. 48 hours
d. The key does not expire by default
Answer: d. The key does not expire by default

20. Which Redis command is used to check if a key exists?

a. EXISTS
b. KEYEXISTS
c. HASKEY
d. CONTAINSKEY
Answer: a. EXISTS

21. What is a Redis transaction?

a. A way to group multiple Redis commands into a single atomic operation
b. A way to encrypt data stored in Redis
c. A way to schedule Redis commands for execution at a later time
d. A Redis data type
Answer: a. A way to group multiple Redis commands into a single atomic operation

22. Which Redis command is used to get the length of a list or a string value?

a. LENGTH
b. LEN
c. STRLEN
d. GETLEN
Answer: c. STRLEN

23. What is the purpose of a Redis set data type?

a. Storing an ordered collection of unique elements
b. Storing a map between field and value
c. Storing an unordered collection of unique elements
d. Storing a list of elements
Answer: c. Storing an unordered collection of unique elements

24. Which Redis command is used to remove all the keys of the currently selected Redis database?

a. FLUSHDB
b. FLUSHALL
c. DELETEALL
d. PURGE
Answer: a. FLUSHDB

25. What is Redis Pub/Sub?

a. A way to publish data to a Redis server
b. A way to subscribe to data updates from a Redis server
c. A Redis data type
d. A Redis configuration option
Answer: b. A way to subscribe to data updates from a Redis server

26. Which Redis data type is best suited for representing a chat room where messages need to be sorted by time?

a. Sorted Set
b. Set
c. List
d. Hash
Answer: c. List

27. What does the Redis FLUSHALL command do?

a. Flushes all keys from the selected Redis database
b. Flushes all keys from all Redis databases
c. Flushes all keys with a specific pattern
d. Flushes all expired keys
Answer: b. Flushes all keys from all Redis databases

28. Which Redis command is used to add one or more members to a set?

a. SADD
b. SMEMBERS
c. SADDMEMBER
d. SETADD
Answer: a. SADD

29. What is the primary use of Redis clustering?

a. Load balancing and high availability
b. Data partitioning and replication
c. Data encryption
d. Real-time analytics
Answer: a. Load balancing and high availability

30. Which Redis command is used to retrieve all the members of a set?

a. SMEMBERS
b. SGETALL
c. SETMEMBERS
d. GETSET
Answer: a. SMEMBERS

31. What is the purpose of the Redis KEYS command?

a. Retrieve all keys in the Redis database
b. Retrieve all keys matching a specified pattern
c. Retrieve all keys in a specific Redis cluster
d. Retrieve keys sorted by size
Answer: b. Retrieve all keys matching a specified pattern

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