CLF-C02 Cloud Concepts Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Horizontal scaling means increasing instance size; vertical scaling means adding more instances

  Why it's wrong here

  This option reverses the actual definitions of the two scaling approaches. Horizontal scaling (also called scaling out or in) changes the number of instances in a fleet, for example by launching additional EC2 instances behind a load balancer or removing them in an Auto Scaling group. Vertical scaling (scaling up or down) resizes a single existing instance to a larger or smaller instance type, which for an EC2 instance generally requires a stop and start operation. Therefore, the statement is incorrect because it swaps the fundamental concepts of scaling breadth versus scaling power.

• ✓

  Horizontal scaling adds more instances; vertical scaling increases the size of existing instances

  Why this is correct

  Horizontal scaling adds more instances to a fleet to distribute workload across multiple resources, a process commonly automated by EC2 Auto Scaling and Load Balancing. Vertical scaling increases the size of an existing instance by changing its instance type to one with more CPU, memory, or I/O capacity, which commonly requires a restart and can be constrained by the maximum instance size available. The key distinction is that horizontal scaling increases capacity by adding parallel resources, while vertical scaling increases capacity by making a single resource more powerful. This is the correct definition and the foundation for choosing the right scaling strategy in cloud architectures.

• ✗

  Both scaling types produce identical results and are interchangeable in cloud architectures

  Why it's wrong here

  Although both scaling types can increase overall capacity, they are not interchangeable because they have fundamentally different operational and architectural trade-offs. Horizontal scaling supports elasticity, avoids downtime, and removes the instance as a single point of failure by spreading load across multiple nodes, often enabling stateless designs. Vertical scaling, by contrast, is limited by the maximum instance size offered by the provider, requires a restart to resize an EC2 instance, and actually concentrates risk because failure of that larger instance impacts the entire workload. Thus, the results are not identical; each method suits different reliability, cost, and operational requirements.

• ✗

  Vertical scaling is always preferred because it reduces the number of instances to manage

  Why it's wrong here

  Vertical scaling is not always preferred because it has hard upper limits in instance size, requires downtime to resize an EC2 instance, and creates a single point of failure for the workload it supports. While it can reduce the number of instances to manage and may be simpler for some stateful applications, horizontal scaling is generally favored in cloud architectures for its flexibility, fault tolerance, and ability to scale on demand without interruption. The phrase "always preferred" is the key flaw: vertical scaling might be useful in specific scenarios, such as when an application is not designed for distribution, but it is not universally the best practice.

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