AZ-900 EXAM.docx

**INDEX** Table of Contents {#table-of-contents.TOCHeading} ================= [1.1 Describe Cloud Concepts (25-30%) 2](#describe-cloud-concepts-25-30) [ Define Cloud Computing 2](#define-cloud-computing) [ Describe the Shared Responsibility Model 2](#describe-the-shared-responsibility-model)...

**INDEX** Table of Contents {#table-of-contents.TOCHeading} ================= [1.1 Describe Cloud Concepts (25-30%) 2](#describe-cloud-concepts-25-30) [ Define Cloud Computing 2](#define-cloud-computing) [ Describe the Shared Responsibility Model 2](#describe-the-shared-responsibility-model) [ Define cloud models, including public, private, and hybrid 4](#define-cloud-models-including-public-private-and-hybrid) [ Identify appropriate use cases for each cloud model 5](#identify-appropriate-use-cases-for-each-cloud-model) [ Describe the consumption-based model 7](#describe-the-consumption-based-model) [ Compare cloud pricing models 8](#compare-cloud-pricing-models) [ Describe serverless 9](#describe-serverless) [1.2 Describe the benefits of using cloud services 11](#describe-the-benefits-of-using-cloud-services) [Describe the benefits of high availability and scalability in the cloud 11](#describe-the-benefits-of-high-availability-and-scalability-in-the-cloud) [ Describe the benefits of reliability and predictability in the cloud 11](#describe-the-benefits-of-reliability-and-predictability-in-the-cloud) [ Describe the benefits of security and governance in the cloud 13](#describe-the-benefits-of-security-and-governance-in-the-cloud) [ Describe the benefits of manageability in the cloud 13](#describe-the-benefits-of-manageability-in-the-cloud) [1.3 Describe cloud service types 14](#describe-cloud-service-types) [Describe infrastructure as a service (IaaS) 14](#describe-infrastructure-as-a-service-iaas) [Describe platform as a service (PaaS) 14](#describe-platform-as-a-service-paas) [Describe software as a service (SaaS) 14](#describe-software-as-a-service-saas) [Identify appropriate use cases for each cloud service type (IaaS, PaaS, and SaaS) 15](#identify-appropriate-use-cases-for-each-cloud-service-type-iaas-paas-and-saas) Describe Cloud Concepts (25-30%) ================================ - Define Cloud Computing ---------------------- - Cloud computing is the delivery of computing services over the internet. Computing services include common IT infrastructure such as **virtual machines, storage, databases, and networking.** Cloud services also expand the traditional IT offerings to include things like: - Internet of Things (IoT) - Machine learning (ML) - Artificial intelligence (AI). - Describe the Shared Responsibility Model ======================================== - The Shared Responsibility outlines the division of security responsibilities between Microsoft and the customer when using Azure services. This model clarifies which security tasks are managed by Microsoft and which tasks the customer needs to handle. The responsibilities differ based on the type of cloud service model being used: Infrastructure as a Service (IaaS), Platform as a Service (PaaS), or Software as a Service (SaaS): [Differences by Service Model:] - Infrastructure as a Service (IaaS): - **Customer**: Responsible for the virtual machines, operating systems, applications, data, and network controls. - **Microsoft**: Manages the physical infrastructure, host operating system, and network. - Platform as a Service (PaaS): - **Customer**: Focuses on securing their applications, data, and identity management. - **Microsoft**: Manages the physical infrastructure, network, host operating system, and the platform services. - Software as a Service (SaaS): - **Customer**: Manages data and user access. - **Microsoft**: Takes care of the infrastructure, application, and platform security, ensuring service availability and compliance. - Define cloud models, including public, private, and hybrid ========================================================== - Private cloud - It's a cloud (delivering IT services over the internet) that's used by a single entity. Private cloud provides much greater control for the company and its IT department. However, it also comes with greater cost and fewer of the benefits of a public cloud deployment. Finally, a private cloud may be hosted from your on-site DataCenter. It may also be hosted in a dedicated datacenter offsite, potentially even by a third party that has dedicated that datacenter to your company. - Public cloud - A public cloud is built, controlled, and maintained by a third-party cloud provider. With a public cloud, anyone that wants to purchase cloud services can access and use resources. The general public availability is a key difference between public and private clouds. - Hybrid cloud - A hybrid cloud is a computing environment that uses both public and private clouds in an inter-connected environment. A hybrid cloud environment can be used to allow a private cloud to surge for increased, temporary demand by deploying public cloud resources. Hybrid cloud can be used to provide an extra layer of security. For example, users can flexibly choose which services to keep in public cloud and which to deploy to their private cloud infrastructure. **Difference Between Cloud Models:**  **Multi-cloud** A fourth, and increasingly likely scenario is a multi-cloud scenario. In a multi-cloud scenario, you use multiple public cloud providers. Maybe you use different features from different cloud providers. Or maybe you started your cloud journey with one provider and are in the process of migrating to a different provider. Regardless, in a multi-cloud environment you deal with two (or more) public cloud providers and manage resources and security in both environments. **Azure Arc** Azure Arc is a set of technologies that helps manage your cloud environment. Azure Arc can help manage your cloud environment, whether it\'s a public cloud solely on Azure, a private cloud in your datacenter, a hybrid configuration, or even a multi-cloud environment running on multiple cloud providers at once. **Azure VMware Solution** What if you're already established with VMware in a private cloud environment but want to migrate to a public or hybrid cloud? Azure VMware Solution lets you run your VMware workloads in Azure with seamless integration and scalability. - Identify appropriate use cases for each cloud model =================================================== **Public Cloud** Use Cases: 1. **Scalable Applications**: Ideal for applications that need to scale rapidly, such as e-commerce websites during peak shopping seasons or mobile applications with variable user loads. 2. **Development and Testing**: Provides a flexible environment for development and testing without the need for upfront infrastructure investment. 3. **Disaster Recovery and Backup**: Cost-effective solutions for disaster recovery and backup, allowing organizations to store copies of their data in multiple geographic locations. 4. **Software as a Service (SaaS)**: Using applications hosted by third parties, such as Microsoft Office 365, Salesforce, or Google Workspace. **Private Cloud** Use Cases: 1. **Regulated Industries**: Suitable for industries with strict regulatory requirements, such as healthcare, finance, and government, where data privacy and control are paramount. 2. **Custom Enterprise Applications**: Ideal for large enterprises with specific customization, performance, and integration needs that are not easily met by public cloud services. 3. **High-Performance Computing (HPC)**: For workloads that require significant compute power and low latency, such as scientific simulations, financial modeling, and large-scale data processing. **Hybrid Cloud** Use Cases: 1. **Cloud Bursting**: Allows businesses to handle peak loads by extending on-premises infrastructure to the public cloud temporarily, ensuring seamless scalability. 2. **Disaster Recovery**: Offers a robust disaster recovery solution by replicating data and applications between private and public clouds. 3. **DevOps and Agile Development**: Supports agile development and continuous integration/continuous deployment (CI/CD) pipelines by using the public cloud for development and testing while keeping production environments on-premises. 4. **IoT Applications**: Manages IoT workloads by processing and analyzing data locally (edge computing) while storing long-term data in the public cloud. In summary, each cloud model serves different needs: - **Public Cloud**: Best for scalability, cost-efficiency, and services that do not require extensive customization or sensitive data handling. - **Private Cloud**: Ideal for highly regulated industries, sensitive data, and custom enterprise applications. - **Hybrid Cloud**: Suitable for organizations needing flexibility, compliance, and gradual cloud migration, as well as those looking to optimize their existing infrastructure while leveraging cloud benefits. The relationship between cloud service Types (IaaS, PaaS, SaaS) and cloud deployment models (Public, Private, Hybrid) is about how these services are delivered and consumed within the different types of cloud infrastructures. Here\'s how they interrelate: Infrastructure as a Service (IaaS) - Public Cloud IaaS: - **Example**: AWS EC2, Microsoft Azure VMs, Google Cloud Compute Engine. - **Usage**: Provides scalable and flexible computing resources on a pay-as-you-go basis. Ideal for startups, testing environments, and workloads with variable demands. - Private Cloud IaaS: - **Example**: VMware vSphere, OpenStack deployed on-premises. - **Usage**: Offers dedicated hardware and resources, enhancing security and compliance. Suitable for industries with strict regulatory requirements and sensitive data handling. - Hybrid Cloud IaaS: - **Example**: Azure Stack, AWS Outposts. - **Usage**: Combines public and private IaaS, allowing businesses to scale out to the public cloud during peak times while maintaining critical workloads on private infrastructure. Platform as a Service (PaaS) - Public Cloud PaaS: - **Example**: Google App Engine, Microsoft Azure App Services, AWS Elastic Beanstalk. - **Usage**: Provides a platform for developers to build, deploy, and manage applications without worrying about underlying infrastructure. Ideal for developing scalable web applications and APIs. - Private Cloud PaaS: - **Example**: Red Hat OpenShift, Cloud Foundry deployed on-premises. - **Usage**: Delivers PaaS capabilities within a private cloud environment, ensuring security and compliance for internal development and deployment processes. - Hybrid Cloud PaaS: - **Example**: Azure Arc, Anthos by Google Cloud. - **Usage**: Enables consistent application development and deployment across public and private clouds, facilitating seamless integration and scalability. Software as a Service (SaaS) - Public Cloud SaaS: - **Example**: Microsoft Office 365, Google Workspace, Salesforce. - **Usage**: Provides software applications over the internet, accessible via web browsers. Ideal for general business applications, reducing the need for internal IT management. - Private Cloud SaaS: - **Example**: Custom CRM or ERP solutions deployed on a private cloud. - **Usage**: Offers SaaS applications within a private cloud environment, enhancing control over data and compliance. Suitable for organizations needing custom applications and high security. - Hybrid Cloud SaaS: - **Example**: A combination of on-premises software and public cloud SaaS. - **Usage**: Integrates on-premises applications with public cloud SaaS offerings, allowing businesses to use cloud software while maintaining control over specific sensitive workloads. Summary - **Public Cloud**: Delivers IaaS, PaaS, and SaaS services over the internet using shared infrastructure. Ideal for scalability, flexibility, and cost-efficiency. - **Private Cloud**: Provides IaaS, PaaS, and SaaS services within a dedicated infrastructure, either on-premises or hosted. Suitable for high security, compliance, and control. - **Hybrid Cloud**: Integrates IaaS, PaaS, and SaaS services across both public and private cloud environments. Offers flexibility, scalability, and compliance, enabling optimized resource utilization. In essence, the service models (IaaS, PaaS, SaaS) can be implemented within any of the deployment models (Public, Private, Hybrid) to cater to specific organizational needs, balancing factors such as cost, security, compliance, and scalability. - Describe the consumption-based model ==================================== **Capital expenditure (CapEx)** and **operational expenditure (OpEx).** - CapEx is typically a one-time, up-front expenditure to purchase or secure tangible resources. A new building, repaving the parking lot, building a datacenter, or buying a company vehicle are examples of CapEx. - OpEx is spending money on services or products over time. Renting a convention center, leasing a company vehicle, or signing up for cloud services are all examples of OpEx. *\*NB. Cloud computing falls under OpEx because cloud computing operates on a consumption-based model. With cloud computing, you don't pay for the physical infrastructure, the electricity, the security, or anything else associated with maintaining a datacenter. Instead, you pay for the IT resources you use. If you don't use any IT resources this month, you don't pay for any IT resources*. This consumption-based model has many benefits - - - - Cloud computing is the delivery of computing services over the internet by using a pay-as-you-go pricing model. You typically pay only for the cloud services you use, which helps you: - - - - Compare cloud pricing models ============================ 1\. Pay-as-You-Go (PAYG) - **Description**: Charges are based on actual usage of resources. Users pay for what they use, typically measured in hours or seconds. - **Use Cases**: Suitable for unpredictable workloads, development and testing environments, startups, and short-term projects. - **Advantages**: No upfront cost, flexible, and cost-efficient for variable workloads. - **Disadvantages**: Can become expensive for consistent, long-term usage. 2\. Reserved Instances (RIs) - **Description**: Users commit to using specific resources for a fixed period (e.g., 1 or 3 years) in exchange for a significant discount compared to PAYG. - **Use Cases**: Ideal for steady-state workloads, long-term projects, and predictable usage patterns. - **Advantages**: Cost savings (up to 75% discount), predictable billing. - **Disadvantages**: Requires upfront commitment, less flexibility to scale down. 3\. Spot Instances - **Description**: Users bid for unused cloud capacity at potentially lower prices than PAYG. Availability can fluctuate based on demand. - **Use Cases**: Suitable for flexible, non-critical workloads like batch processing, data analysis, and testing. - **Advantages**: Significant cost savings (up to 90% discount). - **Disadvantages**: Instances can be terminated with little notice, not suitable for critical applications. - Describe Serverless =================== - Serverless computing is a cloud computing execution model where the cloud provider automatically manages the infrastructure, allowing developers to focus on building and running applications without worrying about server management *Key Characteristics:* 1. **Abstraction of Servers**: Developers do not need to manage server infrastructure. The underlying servers, capacity provisioning, and scaling are handled automatically by Azure. 2. **Event-Driven**: Applications and services are triggered by events, such as HTTP requests, database changes, file uploads, or messages from queues. 3. **Scalability**: Azure serverless services automatically scale in response to the workload. This means resources are allocated dynamically, ensuring applications can handle varying traffic loads efficiently. 4. **Pay-Per-Use**: Users are billed based on actual usage rather than pre-allocated capacity. This includes the number of executions, execution time, and resources consumed, which can lead to cost savings. 5. **Managed Services**: Azure provides managed services, such as Azure Functions and Azure Logic Apps, that simplify the development and deployment of serverless applications. *Core Azure Serverless Services:* 1. **Azure Functions**: - **Description**: A serverless compute service that allows you to run event-driven code without having to explicitly provision or manage infrastructure. - **Use Cases**: Real-time data processing, file processing, scheduled tasks, and backend services for mobile applications. - **Features**: Supports multiple programming languages, integrates with other Azure services, and offers built-in monitoring and diagnostics. 2. **Azure Logic Apps**: - **Description**: A cloud service that helps you automate workflows and integrate apps, data, services, and systems across enterprises or organizations. - **Use Cases**: Business process automation, data integration, and orchestrating workflows across different systems. - **Features**: Visual designer for creating workflows, extensive connectors for integration with various services, and built-in monitoring and management. 3. **Azure Event Grid**: - **Description**: An event routing service that allows you to build event-based applications by subscribing to events from various Azure services or custom sources. - **Use Cases**: Real-time event handling, serverless automation, and microservices communication. - **Features**: High-throughput, low-latency event routing, and support for multiple event sources and handlers. 4. **Azure Durable Functions**: - **Description**: An extension of Azure Functions that allows you to write stateful functions in a serverless environment. - **Use Cases**: Long-running workflows, chaining functions, and handling stateful operations. - **Features**: Orchestrate complex workflows, manage state, and monitor and debug functions. *Benefits of Azure Serverless:* 1. **Focus on Code**: Developers can concentrate on writing code and business logic without worrying about infrastructure management. 2. **Cost Efficiency**: Pay only for the compute resources you use, leading to potential cost savings. 3. **Automatic Scaling**: Applications automatically scale based on demand, ensuring optimal performance and resource utilization. 4. **Increased Productivity**: Rapid development and deployment of applications using managed services and tools. 5. **Integration**: Seamless integration with other Azure services and third-party applications, enhancing functionality and interoperability. *Use Cases:* - **Microservices**: Building microservices architectures where each service can be developed, deployed, and scaled independently. - **API Backends**: Creating scalable and cost-effective backends for web and mobile applications. - **Real-Time Processing**: Handling real-time data streams from IoT devices, social media, or telemetry data. - **Automation**: Automating repetitive tasks, such as data synchronization, file processing, and scheduled reporting. - **Event-Driven Applications**: Developing applications that respond to events from various sources, such as user actions, system changes, or external triggers 1.2 Describe the benefits of using cloud services ================================================= Describe the benefits of high availability and scalability in the cloud ======================================================================= +-----------------------------------+-----------------------------------+ | High Availability | Scalability | +===================================+===================================+ | - Maximum availability, | - Scalability refers to the | | regardless of disruptions or | ability to adjust resources | | events that may occur. | to meet demand. The ability | | | to scale means you can add | | | more resources to better | | | handle the increased demand. | +-----------------------------------+-----------------------------------+ | - Azure is a highly available | - Cost Saving. Because the | | cloud environment with uptime | cloud is a consumption-based | | guarantees depending on the | model, you only pay for what | | service. | you use. | +-----------------------------------+-----------------------------------+ | | +--------------+--------------+ | | | | Vertical | Horizaontal | | | | | Scaling | Scaling | | | | +==============+==============+ | | | | - With | - With | | | | | vertical | horizont | | | | | scaling, | al | | | | | if you | scaling, | | | | | were | if you | | | | | developi | suddenly | | | | | ng | experien | | | | | an app | ced | | | | | and you | a steep | | | | | needed | jump in | | | | | more | demand, | | | | | processi | your | | | | | ng | deployed | | | | | power, | resource | | | | | you | s | | | | | could | could be | | | | | vertical | scaled | | | | | ly | out | | | | | scale up | (either | | | | | to add | automati | | | | | more | cally | | | | | CPUs or | or | | | | | RAM to | manually | | | | | the | ). | | | | | virtual | For | | | | | machine. | example, | | | | | Converse | **you | | | | | ly, | could | | | | | if you | add | | | | | realized | addition | | | | | you had | al | | | | | over-spe | virtual | | | | | cified | machines | | | | | the | or | | | | | needs, | containe | | | | | you | rs**, | | | | | could | scaling | | | | | vertical | out. In | | | | | ly | the same | | | | | scale | manner, | | | | | down by | if there | | | | | lowering | was a | | | | | the CPU | signific | | | | | or RAM | ant | | | | | specific | drop in | | | | | ations. | demand, | | | | | | deployed | | | | | | resource | | | | | | s | | | | | | could be | | | | | | scaled | | | | | | in | | | | | | (either | | | | | | automati | | | | | | cally | | | | | | or | | | | | | manually | | | | | | ), | | | | | | scaling | | | | | | in | | | | +--------------+--------------+ | +-----------------------------------+-----------------------------------+ - Describe the benefits of Reliability and Predictability in the cloud ==================================================================== +-----------------------+-----------------------+-----------------------+ | **Reliability** | **Predictability** | | +=======================+=======================+=======================+ | - Reliability is | - Predictability | | | the ability of a | can be focused on | | | system to recover | performance | | | from failures and | predictability or | | | continue to | cost | | | function. It\'s | predictability. | | | also one of the | Both performance | | | pillars of the | and cost | | | Microsoft Azure | predictability | | | Well-Architected | are heavily | | | Framework | influenced by the | | | | Microsoft Azure | | | | Well-Architected | | | | Framework. Deploy | | | | a solution built | | | | around this | | | | framework and you | | | | have a solution | | | | whose cost and | | | | performance are | | | | predictable | | +-----------------------+-----------------------+-----------------------+ | - With a | ***Performance | ***Cost | | decentralized | predictability*** | predictability*** | | infrastructure | | | | design, the cloud | | | | enables you to | | | | have resources | | | | deployed in | | | | regions around | | | | the world. With | | | | this global | | | | scale, even if | | | | one region has a | | | | catastrophic | | | | event other | | | | regions are still | | | | up and running. | | | +-----------------------+-----------------------+-----------------------+ Performance - Performance predictability focuses on predicting the resources needed to deliver a positive experience for your customers. Autoscaling, load balancing, and high availability are just some of the cloud concepts that support performance predictability. Cost - Cost predictability is focused on predicting or forecasting the cost of the cloud spend. With the cloud, you can track your resource use in real time, monitor resources to ensure that you're using them in the most efficient way, and apply data analytics to find patterns and trends that help better plan resource deployments. [Tools You can use:] -  cloud analytics and information, you can predict future costs - Total Cost of Ownership (TCO) or Pricing Calculator to get an estimate of potential cloud spend. - Describe the benefits of security and governance in the cloud ============================================================= +-----------------------------------+-----------------------------------+ | Governance | Security | +===================================+===================================+ | - Set templates help ensure | - If you want maximum control | | that all your deployed | of security, (IaaS) provides | | resources meet corporate | you with physical resources | | standards and government | but lets you manage the | | regulatory requirements | operating systems and | | | installed software, including | | | patches and maintenance. | +-----------------------------------+-----------------------------------+ | - Cloud-based auditing helps | - If you want patches and | | flag any resource that's out | maintenance taken care of | | of compliance with your | automatically, platform as a | | corporate standards and | service or software as a | | provides mitigation | service deployments may be | | strategies | the best cloud strategies for | | | you | +-----------------------------------+-----------------------------------+ | - Software patches and updates | | | may also automatically be | | | applied, which helps with | | | both governance and security. | | +-----------------------------------+-----------------------------------+ - Describe the benefits of manageability in the cloud =================================================== Manageability options: **Management of the cloud** Management of the cloud speaks to managing your cloud resources. In the cloud, you can: - - - - **Management in the cloud** Management in the cloud speaks to how you're able to manage your cloud environment and resources. You can manage these: - - - Using PowerShell. 1.3 Describe cloud service types ================================ - Describe Infrastructure as a Service (IaaS) =========================================== - **Infrastructure as a service (IaaS)** is the most flexible category of cloud services, as it provides you the maximum amount of control for your cloud resources. - In an IaaS model, the cloud provider is responsible for maintaining the hardware, network connectivity (to the internet), and physical security.  - You're responsible for everything else: operating system installation, configuration, and maintenance; network configuration; database and storage configuration With IaaS, you're essentially renting the hardware in a cloud datacenter, but what you do with that hardware is up to you. (Largest Responsibility share with you). - Describe Platform as a Service (PaaS) ===================================== - **(PaaS)** is a middle ground between renting space in a datacenter (infrastructure as a service) and paying for a complete and deployed solution (software as a service). - In a **PaaS**, the cloud provider maintains the physical infrastructure, physical security, and connection to the internet. They also maintain the operating systems, middleware, development tools, and business intelligence services that make up a cloud solution. - In a PaaS scenario, you don\'t have to worry about the licensing or patching for operating systems and databases. - The cloud provider is responsible for maintaining the physical infrastructure and its access to the internet, just like in IaaS. In the PaaS model, the cloud provider will also maintain the operating systems, databases, and development tools.  - You or the cloud provider may be responsible for networking settings and connectivity within your cloud environment, network and application security, and the directory infrastructure. - Describe Software as a Service (SaaS) ===================================== - Software as a service (SaaS) is the most complete cloud service model from a product perspective. With SaaS, you're essentially renting or using a fully developed application. Email, financial software, messaging applications, and connectivity software are all common examples of a SaaS implementation. - While the SaaS model may be the least flexible, it's also the easiest to get up and running. It requires the least amount of technical knowledge or expertise to fully employ. - SaaS is the model that places the most responsibility with the cloud provider and the least responsibility with the user - In a SaaS environment you're responsible for the data that you put into the system, the devices that you allow to connect to the system, and the users that have access. The cloud provider is responsible for physical security of the datacenters, power, network connectivity, and application development and patching. - Identify appropriate use cases for each cloud service type (IaaS, PaaS, and SaaS) ================================================================================= **Infrastructure as a Service (IaaS)** **Use Cases:** 1. **Disaster Recovery**: - **Description**: Establish a reliable and cost-effective disaster recovery solution. - **Example**: Using Azure Site Recovery to replicate on-premises VMs to Azure for quick failover. 2. **Development and Testing**: - **Description**: Provision development and testing environments quickly without upfront hardware costs. - **Example**: Creating isolated test environments using AWS EC2 or Azure VMs. **Platform as a Service (PaaS)** **Use Cases:** 1. **Web and Mobile Apps**: - **Description**: Develop, deploy, and manage web and mobile applications without worrying about underlying infrastructure. - **Example**: Using Azure App Services or Google App Engine for scalable web applications. 2. **Microservices Architecture**: - **Description**: Build and deploy microservices applications with built-in scaling and orchestration. - **Example**: Using AWS Elastic Beanstalk or Azure Kubernetes Service (AKS) for containerized applications. 3. **API Development and Management**: - **Description**: Create and manage APIs securely and efficiently. - **Example**: Using AWS API Gateway or Azure API Management for API lifecycle management. **Software as a Service (SaaS)** **Use Cases:** 1. **Email and Collaboration**: - **Description**: Use cloud-based email and collaboration tools to enhance productivity. - **Example**: Microsoft Office 365 or Google Workspace for email, document sharing, and collaboration. 2. **Customer Relationship Management (CRM)**: - **Description**: Manage customer interactions and data using a cloud-based CRM system. - **Example**: Salesforce or Microsoft Dynamics 365 for customer relationship management. 3. **Enterprise Resource Planning (ERP)**: - **Description**: Integrate core business processes like finance, HR, and supply chain management. - **Example**: SAP S/4HANA or Oracle ERP Cloud for enterprise resource planning.  Summary: - **IaaS** is ideal for disaster recovery, development and testing, lift-and-shift migrations, big data processing, and HPC. - **PaaS** suits web and mobile app development, microservices architecture, API development, business analytics, and automated workflows. - **SaaS** is perfect for email and collaboration, CRM, ERP, HRM, and content management.