Describe the difference between vertical and horizontal scaling.

Describe the difference between vertical and horizontal scaling.

• A. Vertical scaling adds resources to a single node; horizontal scaling adds more nodes.
• B. Vertical scaling adds more nodes; horizontal scaling increases CPU frequency.
• C. Vertical scaling increases resources across a cluster evenly; horizontal scaling adds more nodes.
• D. Vertical scaling is about storage capacity only; horizontal is about memory.

Answer: (A)

Scaling strategies differ in where growth is applied. Vertical scaling means upgrading a single machine by adding more CPU, RAM, or faster storage to handle higher load. Horizontal scaling means adding more machines to the system and spreading work across them, usually with a load balancer so no one node bears all the traffic.

This is why the correct description fits best: it captures the idea of expanding one node versus expanding the number of nodes in a system. Vertical scaling can be simpler to implement but eventually hits hardware limits and may require downtime for upgrades, while horizontal scaling tends to be more scalable and fault-tolerant because multiple machines share the workload, though it requires architecture that supports distributed processing.

The other ideas misstate what gets scaled—CPU frequency alone or storage tweaks don’t describe the fundamental difference between upgrading a single machine versus adding more machines to handle the load.