We are looking to memorize/remember some facts and hopefully even begin to reach a level of understanding, and eventually be able to apply this knowledge to an exam or at work.
First, here are some useful links to introduce you to the topic:
Have a quick read of the below article>
The shared responsibility model is one of the most important concepts in cloud computing and breaks down who is responsible on the Azure platform; Microsoft or the business client.
The four-level shared responsibility model is composed of:
Lets break these down.
The oldest model where the customer or client owns and maintains the servers. This means an upfront expense for a business to order, install and configure the servers themselves at their own location. This gives that business a fixed amount of compute power, if they need more CPU power, ram, or hard drive space it is another purchase order and a wait for delivery and installation. This may also entail higher Operating expenses due to the need for technical staff to install, configure, update, and maintain the hardware.
Infrastructure as a Service (Iaas)
The next level up in the cloud shared responsibility model is IaaS. For IaaS, our sample company rents time on the servers and underlying hardware from a cloud vendor. This removes some of the cost for renting or purchasing property and buildings as well as electrical and cooling costs. It also allows for rapid hardware scaling since our sample company can now increase their compute power as their needs grow without ordering equipment to be delivered. Remember the equipment is now “in the cloud” aka someone else’s computers.
Importantly, IasS is highly configurable and gives maximum flexibility for our example company. The infrastructure level allows our company to install the exact operating system and virtual machines that meet their needs, giving them full customization options. This is opposed to our next cloud level, a shared responsibility model, Platform as a Service (PaaS)
Platform as a Service (PaaS)
This abstracts away the hardware layer so that a company/client can work on development of applications or services. This means using pre-configured operating systems and Virtual machines. While this does not prevent some minor customization of the servers the point is to use more fixed Operating systems and Virtual machines so the company can focus on their business model of developing their applications and services. If O/S or VM customization is needed then IaaS should have been chosen.
Software as a Service (SaaS)
The Last and upper level of the cloud shared responsibility model is Saas). At this level the cloud provider, provides (and maintains/updates) the hardware and software. Our sample client company just consumes the online Software. Examples of this would be Gmail, office 365, or any other customer resource management software applications (CRM). Our sample company is less interested in software development and just uses the cloud providers software solution to help their business.
Look at the graphic below so see a visual of the various levels of the cloud shared responsibility model.
Finally let us look at how this knowledge can be used to pass the Microsoft Azure AZ-900 fundamentals exam.
If an exam question discusses large capital expenditures than that is “on-premises” where the company pays for hardware to be delivered.
A question regarding IaaS would have some information that the client needs to customize the operating system or virtual machines to meet their business needs.
If a question refers to developing and does not mention virtual machines or operating systems, then that would be referring to PaaS
Finally, for a question regarding a business case where the company just uses a prebuilt software solution, the answer is SaaS
One tricky question is where the client mini case study discusses the need to use a SQL database this comes in both an IaaS and a PaaS solution. Look for a mention of virtual machines which would put the solution in the IaaS category (SQL on Virtual Machines) and not PaaS such as Azure SQL managed Instance.
This covers the four standard levels of the cloud shared responsibility model. Hopefully, this helps you along your Azure learning journey, and if applicable good luck on your AZ900 Foundation exam!
This shared responsibility model covers multiple vendors and how they incorporated the shared responsibility model. This is NOT Azure specific, but the knowledge and especially the concepts will help you in your cloud career.