The public cloud model allows for easy accessibility of systems and services over the internet for general use. Major companies like Amazon, Google, and Microsoft offer public cloud services on a pay-per-use basis, eliminating the need for users to host services on their own. Public clouds offer benefits like flexibility, scalability, and low costs but have potential disadvantages around security and customization compared to private clouds.

1. Public Cloud
Model
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2. Definition of Public Cloud
• Type of cloud hosting that easily allows the accessibility of systems & its
services to its clients/users.
• The public cloud is defined as computing services offered by third-party providers
over the public Internet, making them available to anyone who wants to use or
purchase them.
• An IT model where on-demand computing services and infrastructure are
managed by a third-party provider and shared with multiple organizations using
the public Internet.
• Public cloud service providers may offer cloud-based services such as
infrastructure as a service (IaaS), platform as a service (PaaS), or software as a
service (Saas) to users for either a monthly or pay-per-use fee, eliminating the
need for users to host these services on site in their own data center.

3. They may be free or sold on-demand, allowing customers to pay only
per usage for the CPU cycles, storage, or bandwidth they consume.
Some examples of companies that provide public cloud facilities are
IBM, Google, Amazon, Microsoft, etc.
This cloud service is open for use.

4. This type of cloud computing is a true specimen of cloud hosting, where the
service providers render services to various clients.
From the technical point of view, there is the least difference between private
clouds and public clouds along with the structural design. Only the security level
depends based on the service providers and the type of cloud clients use.
The public cloud is better suited for business purposes for managing the load.
This type of cloud is economical due to the decrease in capital overheads.

5. • Public cloud makes computing resources available to anyone for purchase.
Multiple users typically share the use of a public cloud. In contrast, private
cloud involves cloud-based services that are hosted within an
organization’s own private servers.
• Unlike private clouds, public clouds can save companies from the expensive
costs of having to purchase, manage, and maintain on-premises hardware
and application infrastructure - the cloud service provider is held
responsible for all management and maintenance of the system.
• Public clouds can also be deployed faster than on-premises infrastructures
and with an almost infinitely scalable platform.

6. • Every employee of a company can use the same application from any
office or branch using their device of choice as long as they can access
the Internet.
• While security concerns have been raised over public cloud
environments, when implemented correctly, the public cloud can be
as secure as the most effectively managed private cloud
implementation if the provider uses proper security methods, such as
intrusion detection and prevention systems (IDPS).

7. • Public Cloud allows
systems and services to be
easily accessible to
general public.
• The IT giants such as
Google, Amazon and
Microsoft offer cloud
services via Internet.
• The Public Cloud Model is
shown in the diagram
below.

9. Why Public Cloud?
• Many enterprise businesses look to public cloud as a way to scale existing IT resources on
demand without committing to expanding their physical IT infrastructure.
• For instance, instead of purchasing a physical desktop machine, a company can purchase
a virtual desktop license.
• The virtual desktop can be spun up or deactivated in minutes and can be located
anywhere, instantly.
• The public cloud is also a popular solution for storage needs since data stored on a public
cloud is backed up and accessible from anywhere.
• There are many different types of storage plans, and data that does not need to be accessed
frequently can often be stored in the public cloud very cheaply.
• For companies that host an application with periods of peak usage, the public cloud makes
perfect sense because the extra computing power is only needed for a short time.

10. • Using the public cloud can save businesses money in a couple of different
ways:
• Lower equipment purchase costs: Because employees can access and
pay for cloud-based resources only when they need them, using public
cloud–based desktops and applications is often less expensive than
purchasing physical IT equipment or software packages that may or
may not be used and will need to be maintained.
• Lower equipment maintenance costs: With public cloud-based
services, the cost of maintaining IT equipment is also passed on to the
cloud service provider.

11. A small or new business may have an easier time migrating
applications to the public cloud; organizations with a large legacy IT
infrastructure and applications have more to consider and plan for.
However, more and more enterprise businesses are moving toward
public cloud as one element of a multi-faceted IT plan.
This way, they can access the benefits of public cloud while also
maintaining the different benefits that come with on-premises
architecture and private cloud options.

12. How Public Cloud works
• A public cloud relies on a virtualized environment to provide an
extension of a company’s IT infrastructure, allowing that company to
host certain aspects of its infrastructure and services on virtual
servers that are offsite and owned by a third party.
• Public cloud service providers have different strengths, and they offer
a wide variety of services and pricing models.

13. • Companies that are considering a migration to public cloud
need to carefully consider their options when it comes to
choosing a provider, especially if they will be locked into a long-
term contract.
• Careful planning can help to keep costs down on monthly cloud
services bills, but organizations with unpredictable public cloud
usage may find it hard to avoid spending a lot of money on
public cloud services when usage suddenly surges.

14. • Because servers in the public cloud share data from multiple
companies, security in public cloud is another issue that IT managers
will want to weigh.
• Encrypting data is a good way to ensure stronger security, but if you
are using a combination of public and private cloud (also known as a
hybrid cloud), not all encryption platforms work across both public
and private clouds.
• There is also an inherent security risk whenever data is moved
between a private data center or private cloud and a public cloud.

15. • One last consideration is the location of your public cloud service
provider.
• Data privacy laws in many countries require certain types of data to
be stored in-country.
• These laws change frequently, so it’s a good idea to choose a cloud
service provider that is located in your country and can confirm that
the servers where your data will be stored are local and in compliance
with regional laws.
• There is also the issue of latency—if your data is being hosted on a
different continent, it may take longer than if it were stored close by.

16. Benefits
• There are many benefits
of deploying cloud as
public cloud model.
• The following diagram
shows some of those
benefits:

17. • Cost Effective
• Since public cloud shares same resources with large number of customers it turns out inexpensive.
• Reliability
• The public cloud employs large number of resources from different locations. If any of the resources fails,
public cloud can employ another one.
• Flexibility
• The public cloud can smoothly integrate with private cloud, which gives customers a flexible approach.
• Location Independence
• Public cloud services are delivered through Internet, ensuring location independence.
• Utility Style Costing
• Public cloud is also based on pay-per-use model and resources are accessible whenever customer needs
them.
• High Scalability
• Cloud resources are made available on demand from a pool of resources, i.e., they can be scaled up or down
according the requirement.

18. Advantages of the Public Cloud Model
Flexible Reliable High Scalable Low cost Place
independence

19. Advantages of the
Public Cloud Model
• Minimal Investment: Because it is a pay-per-use
service, there is no substantial upfront fee, making it
excellent for enterprises that require immediate
access to resources.
• No setup cost: The entire infrastructure is fully
subsidized by the cloud service providers, thus there
is no need to set up any hardware.
• Infrastructure Management is not required: Using
the public cloud does not necessitate infrastructure
management.
• No maintenance: The maintenance work is done by
the service provider (not users).
• Dynamic Scalability: To fulfill your company’s needs,
on-demand resources are accessible.

20. Disadvantages of the Public Cloud Model
Low Security / Less Secured
In public cloud model, data is hosted off-site and
resources are shared publicly, therefore does not
ensure higher level of security.
Less Customizable / Poor
Customizable
It is comparatively less customizable than private
cloud.

21. • The security offered by cloud
service providers is steadily
outstripping on-premises security
solutions.
• With the growing popularity
of containers—which can greatly
enhance security in cloud native
application architectures—and
new public cloud offerings that
include vendor-certified
compliance with industry
standards and regulations, it’s
becoming easier than ever to
maintain a security posture that’s
at least as strong as what can be
achieved with on-premises
infrastructures.

22. • According to security software provider McAfee,
today 52% of companies experience better security
in the cloud than on-premises. (link resides outside
of ibm.com)
• Gartner has predicted that by this year (2020),
infrastructure as a service (IaaS) cloud workloads
will experience 60% fewer security incidents than
those in traditional data centers (PDF, 2.3 MB) (link
resides outside of ibm.com).
• Nonetheless, maintaining such security standards
in the public cloud demands different governance
procedures and employee skillsets than in legacy IT
environments.
• Cloud security requires strong access management,
encryption for data at rest, in transit, or in use, and
excellent visibility to monitor, detect and manage
cyberthreats.