Azure Fundamentals AZ-900
120 flashcards by MentisLibrary
Cloud concepts, core Azure architecture and services, identity and security, governance, cost tools and management tooling, mapped to the AZ-900 Azure Fundamentals exam objectives for first-time cloud certification candidates.
- What is cloud computing?
- The delivery of computing services such as servers, storage, databases, networking, software and analytics over the internet, paid for as they are used rather than bought up front.
- In the shared responsibility model, which responsibilities always stay with the customer?
- Data and information, devices (endpoints), accounts and identities, and access management, no matter which service type is used.
- In the shared responsibility model, which responsibilities always belong to Microsoft?
- The physical datacenter, physical network and physical hosts, for every service type.
- IaaS, PaaS, SaaS: which model shifts the most responsibility to the cloud provider?
- SaaS. The provider runs the application, runtime, operating system and hardware; the customer manages only data, identities and access.
- Infrastructure as a Service (IaaS)
- Renting virtualized compute, storage and networking; the customer installs and manages the operating system and everything above it.
- Platform as a Service (PaaS)
- A managed environment for building and running applications where the provider handles the OS, runtime, patching and scaling; the customer deploys code and data.
- Software as a Service (SaaS)
- A complete application delivered over the internet on a subscription, with the provider responsible for the whole stack.
- Public, private and hybrid cloud
- Public cloud is shared infrastructure owned by a provider; private cloud is dedicated to one organization (on its own or a third party's hardware); hybrid combines the two with data and apps moving between them.
- Capital expenditure (CapEx) vs operational expenditure (OpEx)
- CapEx is up-front spending on physical assets that depreciate over time; OpEx is ongoing pay-as-you-go spending on services. Cloud shifts spending from CapEx to OpEx.
- What is the consumption-based model?
- Pay only for the resources you actually use, with no up-front cost and the ability to stop paying when you stop using a resource.
- High availability
- The ability of a system to stay operational for a high percentage of time, expressed as the uptime percentage in the service level agreement.
- Scalability vs elasticity
- Scalability is the ability to add or remove resources to meet demand; elasticity is doing that automatically as demand rises and falls.
- Vertical scaling vs horizontal scaling
- Vertical scaling (scale up or down) changes the size of a single resource; horizontal scaling (scale out or in) changes the number of resources.
- Reliability in cloud terms
- The ability of a system to recover from failures and continue functioning, usually through redundancy across zones and regions.
- Predictability in the cloud
- Two kinds: performance predictability (autoscaling, load balancing and HA keep response times steady) and cost predictability (tracking and forecasting spend in real time).
- What is a service level agreement (SLA)?
- A formal commitment from Microsoft to a specific uptime or connectivity percentage for a service, with service credits if the target is missed.
- How much downtime per month does a 99.9% SLA allow?
- About 43 minutes in a 30-day month; 99.99% allows about 4.3 minutes and 99.999% about 26 seconds.
- How is a composite SLA calculated for an app that depends on several services?
- Multiply the individual SLAs. A web app at 99.95% using a database at 99.99% has a composite SLA of roughly 99.94%.
- What is an Azure region?
- A geographic area containing one or more datacenters connected by a low-latency network, chosen when you deploy a resource.
- Region pairs
- Each Azure region is paired with another in the same geography, usually at least 300 miles apart, so platform updates roll out to one at a time and one of the pair is prioritized for recovery in a widespread outage.
- Availability zones
- Physically separate datacenters within a region, each with independent power, cooling and networking, connected by high-speed private fiber. Regions that support zones have at least three.
- Sovereign regions
- Isolated Azure instances for regulatory or compliance reasons: Azure Government for US agencies and partners, and Azure China operated by 21Vianet.
- Rules for resource groups
- Every resource lives in exactly one resource group, groups cannot be nested, and a group's resources may sit in different regions from the group itself.
- What happens when you delete a resource group?
- Every resource inside it is deleted too. This is the standard way to tear down an environment in one action.
- What two boundaries does an Azure subscription define?
- A billing boundary (each subscription produces its own invoice) and an access control boundary (policies and role assignments applied at subscription scope).
- Management groups
- Containers above subscriptions that let you apply policy, access and compliance settings across many subscriptions at once, in a hierarchy up to six levels deep below the root.
- Order the Azure scope hierarchy from top to bottom
- Management group, subscription, resource group, resource. Settings applied at a higher level are inherited by everything below.
- What is Azure Resource Manager (ARM)?
- The deployment and management service for Azure: a single control plane that every tool (portal, CLI, PowerShell, SDKs, REST) calls to create, update and delete resources.
- Azure Virtual Machines
- IaaS compute offering full control over the guest operating system, useful for lift-and-shift, custom software and workloads that need OS-level access.
- Virtual Machine Scale Sets
- A group of identical, load-balanced VMs that can automatically increase or decrease in count based on demand or a schedule.