Hello and welcome to this lecture where I shall explain some of the different deployment models used when adopting Cloud technology. Typically within Cloud computing, there are three different Cloud model types, each offering different levels of management, flexibility, security and resilience, and these are Public, Private and hybrid. Let's start with the Public Cloud. 

A Public Cloud model is where a vendor makes available use of shared infrastructure including, but not limited to, compute, storage, database and network 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 physical location of their data, but they will be able to specify the geographic region in which it resides to aid with data latency depending on where you 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, as this will provide the best overall performance for them. All back and maintenance of the physical location services such as power calling et cetera, along with the physical maintenance of hosts such as hardware failures, will be maintained by the Cloud vendor and seemingly 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 it's 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 premise. 

How this differs from a typical on-premise server farm approach, is that the same Cloud principals are applied to the design such as the use of virtualization, creating a pool of shared computer storage and network resources, making use of scalability and on-demand provision. With this approach, more capital expenditure is requited to acquire the host and the data center 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 cost will also increase. compared to that of a Public Cloud model. As you may have already guessed, a hybrid Cloud is a model that makes use of both Public and Private Clouds. This model may be used for seasonal burst traffic or for 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 of the Private Cloud. 

This makes 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 also contain the same negatives from both solutions too. Hybrid Clouds are normally short-term configurations, maybe for test and dev purposes, and can often be a transitional state for enterprises before moving a service to reside purely in the Public Cloud. 

This table highlights some of the differences between the Cloud types. So feel free to pause the video just to examine the contents of this table just so you really understand the differences. That brings me to the end of this lecture covering the three main deployment types of Cloud technology. For the remainder of this course, I'll be primarily focusing on Public Cloud deployments. Coming up in the next lecture, I'll be looking at some of the key Cloud concepts to be aware of.