Typically within cloud computing, there are four different cloud model types, each offering different levels of management and security. These are public, private, hybrid, and community. Let's start with the public cloud.

A public cloud model is where the vendor makes available the use of shared infrastructure and resources that can be provisioned on-demand and typically accessed over the internet for public usage. The consumer will never see the hardware used, nor know the exact location of their data, but they will be able to specify the geographic location to aid with speed of performance, depending on where end users are located. It makes sense from a design perspective to host your infrastructure as close to the geographical region as your customers or end users are in order to reduce latency for your users. All back-end maintenance of the physical location services, such as power, calling (ph 00.50), etc. along with the physical maintenance of hosts, such as hardware failures, will be maintained by the vendor and invisible to the end user. As a general rule, you can access your services on the public cloud from anywhere as long as you have an internet connection.

A private cloud is different to a public cloud in that the infrastructure is privately hosted, managed, and owned by the individual company using it, giving greater and more direct control of its data. Enterprises who wish to keep a tighter grasp of security control may adopt this architecture. As a result, the hardware is usually held on-premises. How this differs from a typical on-premises server farm approach is that the same cloud principles are applied to the design, such as the use of virtualisation, creating a pool of shared compute, storage, and network resources, making use of scalability and on-demand provisioning. With this approach, more capital expenditure is required to acquire the hosts and the data centre that they will physically reside in. Not only this, additional resource will be needed for the day-to-day operations and maintenance of this equipment, and so your daily operational costs will also increase compared to the other public cloud model.

A hybrid cloud, as you may have already guessed, is a cloud model that makes use of both public and private clouds. This model may be used for seasonal burst traffic or disaster recovery. A hybrid model is established when a network link is configured between the private cloud to services within the public cloud, essentially extending the logical internal network. This takes the benefits given from both the public and private models and allows you to architect your services in the most appropriate model. However, be aware that they may also contain the negatives from both solutions too. Hybrid clouds are normally short-term configurations, maybe for test and development purposes, and can often be a transitional state for enterprises before moving a service to a public cloud model only.

A community cloud is a type of Cloud computing service that is shared by several organisations with similar needs and concerns, such as security, compliance, or specific regulatory requirements. It allows these organisations to collaborate and share resources whilst still benefiting from the scalability and flexibility of cloud services. Essentially, it combines the advantages of both public and private clouds, providing a shared infrastructure that is tailored to meet the specific needs of the community. To give an overview of some of the differences between the cloud types, please take a look at this table, and for the rest of this lesson I will focus mainly on public cloud deployments.

Cloud Deployment Models | ITL3 A3.1 |

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