Week -4

1.Which of the following statements about Bloom filters is true?

a. Bloom filters guarantee no false negatives
b. Bloom filters use cryptographic hashing functions
c. Bloom filters may produce false positives but no false negatives
d. Bloom filters are primarily used for sorting large datasets

Option a: Bloom filters guarantee no false negatives - Incorrect. Bloom filters

can produce false positives (indicating an element is present when it's not), but
they guarantee no false negatives (indicating an element is absent when it's
present).

Option b: Bloom filters use cryptographic hashing functions - Incorrect. While

cryptographic hashing functions can be used, they are not a requirement. Bloom
filters typically use multiple hash functions.

Option c: Bloom filters may produce false positives but no false negatives -
Correct. This is the fundamental property of Bloom filters.

Option d: Bloom filters are primarily used for sorting large datasets - Incorrect.
Bloom filters are primarily used for approximate membership testing.

2. How does CAP theorem impact the design of distributed systems?

A) It emphasizes data accuracy over system availability

B) It requires trade-offs between consistency, availability, and partition tolerance

C) It prioritizes system performance over data security

D) It eliminates the need for fault tolerance measures

Option A: It emphasizes data accuracy over system availability - Incorrect.

The CAP theorem does not prioritize data accuracy; rather, it highlights the
 trade-offs between consistency, availability, and partition tolerance in distributed
systems.

Option B: It requires trade-offs between consistency, availability, and

partition tolerance - Correct. The CAP theorem states that in the presence of a
network partition, a distributed system can only guarantee either consistency or
availability, but not both.

Option C: It prioritizes system performance over data security - Incorrect.

The CAP theorem does not address performance or security; it focuses
specifically on the consistency, availability, and partition tolerance trade-offs in
distributed systems.

Option D: It eliminates the need for fault tolerance measures - Incorrect.

The CAP theorem does not eliminate the need for fault tolerance; in fact, it
highlights the challenges that arise in maintaining consistency and availability
when partitions occur.

3. Which guarantee does the CAP theorem consider as mandatory for a distributed
system?
a. Consistency
b. Availability
c. Partition tolerance
d. Latency tolerance

Option a: Consistency - Incorrect. The CAP theorem states that it's impossible
to achieve all three guarantees (Consistency, Availability, and Partition tolerance)
simultaneously in a distributed system.

Option b: Availability - Incorrect. Availability is not guaranteed if partition

tolerance is required.

Option c: Partition tolerance - Correct. The CAP theorem states that partition
tolerance is essential for distributed systems, as network partitions are inevitable.

Option d: Latency tolerance - Incorrect. Latency tolerance is not explicitly

mentioned in the CAP theorem.
4.What consistency level in Apache Cassandra ensures that a write operation is
acknowledged only after the write has been successfully written to all replicas?
a. ONE
b. LOCAL_ONE
c. LOCAL_QUORUM
d. ALL

Option a: ONE - Incorrect. ONE requires only one replica to acknowledge the
write.

Option b: LOCAL_ONE - Incorrect. LOCAL_ONE requires one replica within

the same datacenter to acknowledge the write.

Option c: LOCAL_QUORUM - Incorrect. LOCAL_QUORUM requires a quorum

of replicas within the same datacenter to acknowledge the write.

Option d: ALL - Correct. ALL requires all replicas to acknowledge the write
before returning a response.

5. How does Zookeeper contribute to maintaining consistency in distributed systems?

A) By managing data replication

B) By providing a centralized configuration service

C) By ensuring data encryption

D) By optimizing data storage

Option A: By managing data replication – Incorrect. Zookeeper’s role is more

about coordination, not directly managing data replication.

Option B: By providing a centralized configuration service – Correct.

Zookeeper contributes to maintaining consistency in distributed systems by

providing a centralized coordination and configuration service, ensuring
consistent synchronization across distributed nodes.
 Option C: By ensuring data encryption – Incorrect. Zookeeper doesn't handle
encryption.

Option D: By optimizing data storage – Incorrect. Zookeeper is not involved

in optimizing data storage.

Explanation:

Centralized Configuration: ZooKeeper acts as a centralized service where

distributed applications can store and retrieve configuration information. This
helps in ensuring that all nodes in the distributed system have consistent
configuration settings, reducing the chances of configuration mismatches or
inconsistencies.

6. A ___________ server is a machine that keeps a copy of the state of the entire
system and persists this information in local log files.
a) Master
b) Region
c) Zookeeper
d) All of the mentioned

Option A: Master – Incorrect. The master server may manage parts of the
system but does not persist the full system state in local logs.

Option B: Region – Incorrect. A region server manages a subset of data, but it

doesn’t maintain the full system state or persist it in logs.

Option C: Zookeeper – Correct. Zookeeper maintains a consistent view of the

system’s state and stores this information in local log files for fault tolerance and
recovery.

Option D: All of the mentioned – Incorrect. Only Zookeeper is responsible for

persisting the state of the entire system in local logs.

Explanation:

Master Server: A master server typically coordinates tasks within a cluster but
doesn't necessarily store the entire system state.
 Region Server: This term is often used in context of distributed databases like
HBase, where region servers manage specific data partitions. They wouldn't hold
the entire system state.

Zookeeper

Zookeeper is a centralized service that coordinates and manages distributed

systems. It keeps a copy of the system's state and persists this information in
local log files. This allows it to provide services such as naming, configuration
management, and synchronization.

While a Master node might also have some state information, its primary role is
often different, such as coordinating tasks or managing data. A Region node is
typically a unit within a larger distributed system, and its role might involve
managing specific data or tasks.

7.What is Apache Zookeeper primarily used for in Big Data ecosystems?

A) Data storage

B) Data processing

C) Configuration management

D) Data visualization

Option A: Data storage – Incorrect. Zookeeper is not designed for storing large
amounts of data; its main purpose is coordination, not data storage.

Option B: Data processing – Incorrect. Zookeeper does not process data; it

provides coordination services for distributed systems.

Option C: Configuration management – Correct. Zookeeper is primarily used

for configuration management, leader election, and synchronization in distributed
systems within Big Data ecosystems.

Option D: Data visualization – Incorrect. Zookeeper has no role in data

visualization. Its function is more about system coordination and management.
8. Which statement correctly describes CQL (Cassandra Query Language)?
a. CQL is a SQL-like language used for querying relational databases
b. CQL is a procedural programming language used for writing stored procedures in
Cassandra
c. CQL is a language used for creating and managing tables and querying data in
Apache Cassandra
d. CQL is a scripting language used for data transformation tasks in Cassandra

Option A: CQL is a SQL-like language used for querying relational

databases – Incorrect. While CQL is SQL-like, Cassandra is a NoSQL
database, not a relational database.

Option B: CQL is a procedural programming language used for writing

stored procedures in Cassandra – Incorrect. CQL is not a procedural
language, nor is it used for writing stored procedures
.

Option C: CQL is a language used for creating and managing tables and
querying data in Apache Cassandra – Correct. CQL is primarily used in
Cassandra for creating, managing tables, and querying data.

Option D: CQL is a scripting language used for data transformation tasks in

Cassandra – Incorrect. CQL is not a scripting language and is not designed for
data transformation tasks.

9.Which aspect of CAP theorem refers to a system's ability to continue operating

despite network failures?

A) Consistency

B) Accessibility

C) Partition tolerance

D) Atomicity

Option A: Consistency – Incorrect. Consistency refers to ensuring that all

nodes see the same data at the same time, not handling network failures.
 Option B: Accessibility – Incorrect. Availability refers to the system's ability to
respond to requests, but does not specifically address network partitioning.

Option C: Partition tolerance – Correct. Partition tolerance refers to the

system's ability to continue functioning even when network failures or partitions
occur.

Option D: Atomicity – Incorrect. Atomicity is a concept related to transactions,

ensuring that operations are fully completed or not at all, not related to network
failures.

10.Why are tombstones used in distributed databases like Apache Cassandra?

a. To mark nodes that are temporarily unavailable
b. To mark data that is stored in multiple replicas
c. To mark data that has been logically deleted
d. To mark data that is actively being updated

Option a: To mark nodes that are temporarily unavailable - Incorrect.

Tombstones are not used to mark unavailable nodes.

Option b: To mark data that is stored in multiple replicas - Incorrect.

Tombstones are not used to mark data replication.

Option c: To mark data that has been logically deleted - Correct. Tombstones
are used to mark data that has been deleted but still exists in the system for a
certain period to prevent accidental overwrites.

Option d: To mark data that is actively being updated - Incorrect. Tombstones

are not used to mark data that is being updated.