Explanation

Section: Understand Azure Pricing and Support

Explanation
A private cloud is hosted in your datacenter. Therefore, you cannot close your datacenter if you are using a private cloud.
A public cloud is hosted externally, for example, in Microsoft Azure. An organization that hosts its infrastructure in a public cloud can close its data center.
Public cloud is the most common deployment model. In this case, you have no local hardware to manage or keep up-to-date everything runs on your cloud provider's hardware.
Microsoft Azure is an example of a public cloud provider.
In a private cloud, you create a cloud environment in your own datacenter and provide self-service access to compute resources to users in your organization.
This offers a simulation of a public cloud to your users, but you remain completely responsible for the purchase and maintenance of the hardware and software services you provide.
https://docs.microsoft.com/en-gb/learn/modules/principles-cloud-computing/4-cloud-deployment-models

Explanation
The SLA for virtual machines guarantees 'uptime'. The amount of uptime guaranteed depends on factors such as whether the VMs are in an availability set or availability zone if there is more than one VM, the distribution of the VMs if there is more than one or the disk type if it is a single VM.
The SLA for Virtual Machines states:
* For all Virtual Machines that have two or more instances deployed across two or more Availability Zones in the same Azure region, we guarantee you will have Virtual Machine Connectivity to at least one instance at least 99.99% of the time.
* For all Virtual Machines that have two or more instances deployed in the same Availability Set or in the same Dedicated Host Group, we guarantee you will have Virtual Machine Connectivity to at least one instance at least 99.95% of the time.
* For any Single Instance Virtual Machine using Premium SSD or Ultra Disk for all Operating System Disks and Data Disks, we guarantee you will have Virtual Machine Connectivity of at least 99.9%.
References:
https://azure.microsoft.com/en-us/support/legal/sla/summary/
https://azure.microsoft.com/en-us/support/legal/sla/virtual-machines/v1_9/