MSDN Documentation

1. Public Cloud

Public clouds are owned and operated by third-party cloud service providers (like Microsoft Azure, Amazon Web Services, Google Cloud Platform). They deliver computing services—servers, storage, databases, networking, software, analytics, and intelligence—over the Internet. Resources are shared among multiple organizations, offering high scalability and cost-effectiveness. Users typically pay only for what they consume.

Key Characteristics:

• High scalability and elasticity
• Pay-as-you-go pricing
• No hardware maintenance for the user
• Shared infrastructure

Use Cases: Web hosting, development and testing environments, disaster recovery, applications with fluctuating demand.

2. Private Cloud

A private cloud is cloud computing resources used exclusively by a single business or organization. It can be physically located on the company's on-premises data center or hosted by a third-party service provider. The key distinction is that the infrastructure is dedicated to one organization, offering greater control, security, and customization.

Key Characteristics:

• Enhanced security and privacy
• Greater control and customization
• Dedicated resources
• Higher upfront costs and management overhead

Use Cases: Organizations with strict regulatory compliance requirements, sensitive data, or specific performance needs.

3. Hybrid Cloud

Hybrid cloud combines public and private clouds, allowing data and applications to be shared between them. This model offers the best of both worlds, leveraging the scalability and cost-effectiveness of the public cloud while maintaining the security and control of a private cloud for sensitive workloads. Organizations can place critical workloads on a private cloud and less sensitive ones on a public cloud.

Key Characteristics:

• Flexibility to move workloads between environments
• Optimized for cost and performance
• Increased complexity in management
• Leverages existing investments

Use Cases: Bursting workloads, disaster recovery, tiered data storage, modernizing legacy applications.

An example configuration might look like this:

# On-Premises Private Cloud
server {
    listen 80;
    server_name private.example.com;
    # ... internal configurations ...
}

# Public Cloud (e.g., Azure)
resource "azurerm_virtual_network" "main" {
  name                = "example-vnet"
  resource_group_name = data.azurerm_resource_group.main.name
  location            = data.azurerm_resource_group.main.location
  address_space       = ["10.0.0.0/16"]
}

# Hybrid connectivity is typically established via VPN gateways or ExpressRoute
# ...
                

4. Multi-Cloud

Multi-cloud refers to the use of multiple cloud computing services from more than one cloud provider. This is distinct from hybrid cloud, which typically involves a mix of public and private environments. Organizations adopt multi-cloud strategies to avoid vendor lock-in, leverage best-of-breed services from different providers, improve resilience, and optimize costs.

Key Characteristics:

• Avoids vendor lock-in
• Access to specialized services
• Enhanced resilience and redundancy
• Significant management and integration challenges

Use Cases: Geographic distribution, regulatory compliance across different regions, leveraging unique services from specific providers.