This feature first appeared in the Fall 2020 issue of Certification Magazine. Click here to get your own print or digital copy.

Cloud computing is the de facto technology standard for the majority of people in both their working and personal lives. The convenience and functionality of the cloud paired with powerful mobile devices that enable always on personal and business computing has permanently transformed our world. But, as any sky gazer can tell you, not every cloud looks the same.

There are three different primary cloud computing models: public, private, and hybrid. Each of these cloud models offers different levels of efficiency, stability, and security. Knowing what these differences are and which model best suits the requirements of a business is something every IT professional should have in their skill set.

Let's take a closer look at cloud computing models, the pros and cons of each, and where cloud professionals should focus their training efforts based on industry adoption.

Public clouds

As its name suggests, a public cloud leverages the internet to provide businesses with online computing assets which are hosted on equipment owned by third-party cloud service providers. A company can use its rent-a-cloud to offer products and services to customers over the public internet, along with internal applications and resources available to employees anywhere they have internet access.

Businesses often use public cloud setups to sell software as a service (SaaS) products using B2B (business to business) or B2C (business-to-customer) arrangements. Public clouds offer great convenience to companies as they aren't required to purchase and maintain an internal server/application infrastructure. Instead, the public cloud service providers are responsible for the management of the hardware and software used to host the cloud services.

Another key advantage of public clouds is the speed with which they can be deployed and scaled up or down according to the needs of a business. A company must spend significant time and resources to set up and maintain an onsite server room with the necessary components and protocols, and changes to the business can require costly additions to scale up its IT infrastructure.

By contrast, a public cloud service provider can deploy a new cloud in a fraction of the time required by the above-described on-premises setup. A public cloud provider can also dynamically add or remove resources according to a business's changing requirements.

The main criticism of public clouds has to do with information security concerns. Because public clouds are accessed through the internet, they are arguably at greater risk for cyberattacks or accidental data leaks.

While this is a valid concern, the top public cloud service providers (Amazon, Microsoft, and Google lead this pack) have built their business reputations on providing secure environments. Most can be counted on to provide robust authentication and anti-intrusion measures.

Private clouds

Sometimes a business or organization deals with information that is just too sensitive (or valuable) to keep on external servers owned and operated by someone else. Enter the private cloud, an onsite cloud computing environment owned and managed by the group that deploys it.

Private clouds are the closest thing on the cloud computing market to traditional network enterprises in design and functionality. Private clouds are often used to provide infrastructure as a service (IaaS) and platform as a service (PaaS) products to customers.

The key word with private clouds is internal. A business or organization typically hosts its private cloud on its own property, installed on its own hardware, and administrated by its own onsite IT department. The cloud owners are responsible for providing appropriate information security measures, as well as regular updates to hardware and software as required.

This gives private clouds an edge when it comes to security and privacy. An internal network hosting a private cloud can be configured with information security measures that go well beyond the infosec deployed by public cloud service providers in their environments.

This level of control comes with some financial drawbacks. Onsite server rooms can be costly to build and maintain. Purchasing computing and networking equipment creates capital costs which must be amortized over time. And having a fully-staffed IT department means carrying a higher payroll.

A private cloud's infrastructure is also not as flexible as a that of a public cloud. It is generally more expensive and time-consuming to scale up a private cloud's computing power, should that become required by business growth or expansion of an organization's responsibilities.

Hybrid clouds

There are all types of hybrids in the world: vehicles, golf clubs, orchids, and so forth. And yes, there are hybrid clouds as well. A hybrid cloud is a mixed environment that lets you maintain a private infrastructure for privacy sensitive information assets, while having a public-facing system you can leverage for services that don't require ultra-high security.

Hybrid clouds have a similar level of control as a private cloud, with the flexibility and convenience of a public cloud. For example, hybrid clouds are ideal for setting up a two-tier product system from which customers can choose the level of security and privacy they want to have when using the system.

Another big advantage of hybrid clouds is that companies don't have to take on capital expenses to scale up their IT assets when a temporary increase in demand (such as the holiday shopping season) creates heavy activity spikes. Instead, they can temporarily expand their public cloud resource pool to meet the higher demands of a short-term boom in activity.

Hybrid clouds still require some internal investment in IT assets, however, with the associated costs and requirements of private clouds. There is also a higher level of risk involved with hybrid clouds (compared to private clouds) that must be considered.

Which cloud model should I study?

The glib answer to this question is, all of them. IT professionals who can work with every cloud model will likely find more job opportunities than someone who is only tech-savvy with one model.

Proficiency with all three cloud models also reflects the IT industry's top three cloud computing service providers: Amazon (AWS), Microsoft (Azure), and Google (Google Cloud). All three companies offer a combination of public, private, and hybrid cloud solutions.

In fact, several popular cloud computing training and certification programs come from these three top cloud service vendors. Some of these certifications include:

Google Certified Professional Cloud Architect

Google Certified Professional Data Engineer

Amazon Web Services (AWS) Certified Solutions Architect

Amazon Web Services (AWS) Certified Developer Associate

Microsoft Certified: Microsoft Azure Fundamentals

Microsoft Certified: Microsoft Azure Administrator Associate

There are also cloud certifications offered by vendor-neutral IT industry organizations. These credentials include Cloud+ (CompTIA), (ISC)²'s Certified Cloud Security Professional, and Certificate of Cloud Security Knowledge (Cloud Security Alliance).

To get a read on which cloud technologies IT professionals (and students) should focus on, it's useful to look at the most popular cloud computing services. The following services make up the lion's share of the cloud computing marketplace:

Cloud storage is probably the most popular cloud computing service worldwide. The global need for data storage is increasing at a somewhat alarming rate. In 2010, the global demand for storage was estimated at 700 exabytes; today, this same estimate is more than 42,000 exabytes (this compared to an estimated global supply of only 24,800 exabytes — a massive shortfall and a growing concern in the IT industry.)

Infrastructure as a Service (IaaS) has gained a lot of traction in recent years as organizations look to reduce the capital expenses and payroll associated with maintaining onsite IT infrastructure. IaaS providers can use virtualization to mimic a traditional networking enterprise, removing the need for server rooms and large IT departments.

Cloud migration is exactly what it sounds like: Take a company's existing onsite hardware and software network infrastructure and move it to the cloud. Some companies can't (or won't) start a new cloud-based enterprise from scratch; they need to take their existing IT assets and migrate them to the cloud — without breaking anything in the process.

Cloud backup has similar roots as cloud storage, but is also closely tied to disaster recovery and business continuity strategies. Cloud backup can be as simple as saving data on a scheduled basis — or it can provide fast turnaround when re-establishing normal business operations after a catastrophic event or large-scale hack. There are even disaster recovery as a service (DRaaS) cloud vendors.

Cloud application programming is arguably the hottest field in software development at the present time. Cloud-based apps power the modern web, and customers have high expectations for these apps — especially mobile apps for smartphones and tablets. Cloud app development is also linked to cloud migration projects, as legacy apps used by businesses and the government often need a cloud-based replacement built to maintain internal requirements.

The sky's the limit

Nearly all of us have come to rely on cloud computing to save our data, provide us with always-on services, and power our digital lives through the myriad of devices we use. Public, private, and hybrid clouds are the technology that makes this scenario possible.

Established IT pros as well as up-and-comers can expect to encounter all three cloud models in their jobs, and should prepare themselves by seeking out a relevant training and certification program.