A cloud provider provides cloud services to cloud consumers. Which of the following does not belong to the service models of the cloud provider?
A. Virtual machines without pre-installed operating systems
B. Platforms which cloud consumers can upload applications
C. Services that are publicly available
D. E-mail services through the web interface
Kindly be reminded that the suggested answer is for your reference only. It doesn’t matter whether you have the right or wrong answer. What really matters is your reasoning process and justifications.
My suggested answer is C. Services that are publicly available.
Services that are publicly available imply a deployment model, public cloud, while other answer options are service models:
- Virtual machines without pre-installed operating systems are IaaS.
- Platforms that cloud consumers can upload applications are PaaS.
- E-mail services through the web interface are SaaS.
Some may argue that almost every cloud provider sells virtual machines with installation options for various operating systems. However, a virtual machine is composed of resources virtualized based on the underlying infrastructure, such as processors, memories, storage, and network connections. Virtual machines without pre-installed operating systems can be realized by importing a virtual machine created on-premise with a pre-installed operating system to the cloud provider.
Software-as-a-Service (SaaS) is a model of service delivery whereby one or more applications and the computational resources to run them are provided for use on demand as a turnkey service. Its main purpose is to reduce the total cost of hardware and software development, maintenance, and operations. Security provisions are carried out mainly by the cloud provider. The cloud consumer does not manage or control the underlying cloud infrastructure or individual applications, except for preference selections and limited administrative application settings.
Platform-as-a-Service (PaaS) is a model of service delivery whereby the computing platform is provided as an on-demand service upon which applications can be developed and deployed. Its main purpose is to reduce the cost and complexity of buying, housing, and managing the underlying hardware and software components of the platform, including any needed program and database development tools. The development environment is typically special purpose, determined by the cloud provider and tailored to the design and architecture of its platform. The cloud consumer has control over applications and application environment settings of the platform. Security provisions are split between the cloud provider and the cloud consumer.
Infrastructure-as-a-Service (IaaS) is a model of service delivery whereby the basic computing infrastructure of servers, software, and network equipment is provided as an on-demand service upon which a platform to develop and execute applications can be established. Its main purpose is to avoid purchasing, housing, and managing the basic hardware and software infrastructure components, and instead obtain those resources as virtualized objects controllable via a service interface. The cloud consumer generally has broad freedom to choose the operating system and development environment to be hosted. Security provisions beyond the basic infrastructure are carried out mainly by the cloud consumer.
Source: NIST SP 800-144
Deployment models broadly characterize the management and disposition of computational resources for delivery of services to consumers, as well as the differentiation between classes of consumers.
A public cloud is one in which the infrastructure and computational resources that it comprises are made available to the general public over the Internet. It is owned and operated by a cloud provider delivering cloud services to consumers and, by definition, is external to the consumers’ organizations.
A private cloud is one in which the computing environment is operated exclusively for a single organization. It may be managed by the organization or by a third party, and may be hosted within the organization’s data center or outside of it. A private cloud has the potential to give the organization greater control over the infrastructure, computational resources, and cloud consumers than can a public cloud.
A community cloud falls between public and private clouds with respect to the target set of consumers. It is somewhat similar to a private cloud, but the infrastructure and computational resources are exclusive to two or more organizations that have common privacy, security, and regulatory considerations, rather than a single organization.
Hybrid clouds are more complex than the other deployment models, since they involve a composition of two or more clouds (private, community, or public). Each member remains a unique entity, but is bound to the others through standardized or proprietary technology that enables application and data portability among them.
Source: NIST SP 800-144