Answer.

Scaling architecture is the selection of approaches that allow the system to handle increasing loads without losing performance and reliability.

There are two types of scaling:

• Vertical (increasing the resources of a single server: CPU, RAM).
• Horizontal (increasing the number of service instances distributed across servers).

Key strategies include:

• Using load balancers to evenly distribute requests.
• Breaking the application into independent services (for example, microservices) so they can be scaled independently.
• Using queues and message brokers to handle peak loads asynchronously.
• Database replication and sharding—different databases handle their data segments.

Example using Kubernetes (horizontal scaling):

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  replicas: 5
  template:
    spec:
      containers:
      - name: myapp
        image: myapp:latest

Key features:

• Allows handling sharp spikes in load without downtime.
• It is easier to achieve fault tolerance with horizontal scaling.
• Careful design of state storage is needed (Stateful vs Stateless services).

Trick questions.

Can a stateful service be scaled as easily as a stateless one?

No, stateful services (e.g., databases) require complex replication and consistency mechanisms. Stateless services can be easily cloned and deployed in multiple instances.

Does a single database easily handle load when vertically scaled?

Only up to a certain limit. Beyond that, a "bottleneck" occurs, and the solution is horizontal scaling through sharding or migrating to distributed DBMS.

Can monolithic applications be scaled effectively?

It may be possible, but with significant limitations—monoliths usually scale poorly horizontally, making it harder to add and maintain copies when load changes.