Cloud Computing and Internet Technology

Cloud computing is the on-demand delivery over a network of a shared pool of configurable resources such as servers, storage, platforms and applications. Resources can be rapidly provisioned and released with minimal provider interaction, pooled among users, elastically scaled and measured for billing or control.

Essential Characteristics

Five characteristics distinguish cloud computing from merely hosting a server at a remote site:

1. On-demand self-service: a customer provisions computing, storage or application capability automatically without waiting for manual provider action.

2. Broad network access: services are available through standard network mechanisms to suitable web, mobile and enterprise clients.

3. Resource pooling: provider resources serve multiple tenants dynamically, with logical isolation and location independence at the abstraction promised to the customer.

4. Rapid elasticity: capacity can scale outward/inward or upward/downward with demand and may appear effectively unlimited.

5. Measured service: use is monitored, controlled and reported, enabling metering, quotas, optimization and usage-based charging.

Cloud architecture from clients and secure API access to alternative service models and common resource foundations, with four deployment models and the five essential characteristics.

A request in the figure is authenticated at a portal or API gateway, scheduled onto pooled virtualized or containerized resources, connected to storage/network services, monitored, scaled and metered. Virtualization is a common enabling mechanism, but cloud computing also requires service automation, pooling, elasticity and measurement.

Cloud Service Models

The service model identifies the abstraction delivered and, consequently, the management boundary between provider and customer.

Model	Provider delivers/manages	Customer mainly manages	Example use
SaaS	Complete hosted application through a browser or API	Users, data, access policy and permitted configuration	Web mail or online office suite
PaaS	Infrastructure, OS, runtime, middleware and managed platform services	Application code, data and application configuration	Telecom self-care API deployed without administering servers
IaaS	Virtual machines, virtual networking and storage on physical infrastructure	Guest OS, patches, middleware, applications, data and network rules	Elastic web-server VMs with block storage

IaaS, PaaS and SaaS service models.

SaaS gives the least infrastructure control and the most provider management; IaaS gives the most customer control and operational responsibility. PaaS trades low-level control for faster application development and deployment.

Deployment Models

Deployment	Ownership and access	Suitable application
Public cloud	Provider-owned infrastructure logically shared among tenants; reached over public or private network links	A public website that scales during demand peaks
Private cloud	Infrastructure dedicated to one organization, operated on its premises or by a host	Subscriber or billing systems under internal policy
Community cloud	Infrastructure shared by organizations with common mission, security or regulatory requirements; operated by members or a provider	A public-sector or industry consortium shares a governed sector platform
Hybrid cloud	Policy-connected private and public environments that coordinate workloads or data	Keep customer records private while public capacity handles bursts or encrypted backup

Cloud deployment models.

Hybrid does not mean an arbitrary collection of unrelated systems: the public and private parts require networking, identity, management and data-movement policies that let them operate together.

Note

Example — Selecting cloud models

A telecom operator keeps subscriber records in a private cloud but exposes a self-care application whose stateless front end scales in a public cloud. This is a hybrid deployment. If developers deploy only their application code while the provider manages the OS, runtime and database platform, that front end consumes PaaS. The deployment model and service model answer different questions and may be combined.

Benefits and Risks

Potential benefit	Risk or limitation
Rapid provisioning and shorter deployment time	Misconfiguration can also be created and replicated rapidly
Elastic capacity for variable demand	Poor scaling rules may increase cost or fail during a demand spike
Resource sharing and reduced initial capital expense	Recurring cost can be unpredictable without metering, budgets and lifecycle control
Broad access and managed services	Provider/network outage and latency affect availability and response time
Provider-managed infrastructure and economies of scale	Migration difficulty, proprietary services and vendor lock-in
Geographic reach and backup options	Data-residency, sovereignty, privacy and legal requirements constrain location and movement

Cloud benefits and corresponding limitations.

Cloud use changes the ownership and concentration of risk; it does not make capacity planning, security, backup or disaster recovery unnecessary. A customer must understand service limits, outage dependencies, exit strategy and total operating cost.

Security and Shared Responsibility

The provider is commonly described as securing the cloud (facilities, physical hardware and provider-controlled service layers), while the customer secures its permitted configuration, identities, workloads and data in the cloud. The exact boundary is contractual and changes with the service model.

Layer or control	IaaS	PaaS	SaaS
Facilities, hardware, core network, hypervisor	Provider	Provider	Provider
Guest OS and patching	Customer	Provider	Provider
Runtime and middleware	Customer	Provider	Provider
Application code	Customer	Customer	Provider
Data classification, user access and allowed configuration	Customer	Customer	Customer

Typical shared-responsibility boundary.

Important controls include:

• Identity and access management: use MFA, least privilege, role separation and prompt revocation rather than shared permanent credentials.

• Data protection: encrypt data in transit and at rest, control keys, classify sensitive data and retain tested backups.

• Isolation and configuration: enforce tenant isolation, private-by-default network/storage policy, patch customer-owned layers and continuously check configuration.

• Visibility and response: collect audit and service logs, monitor anomalies and costs, define incident responsibilities and test recovery.

• Governance: verify location, retention, deletion, compliance, availability objectives and provider exit arrangements.

Encryption does not replace authorization, and provider backup features do not remove the customer’s duty to define retention and test restoration. Shared responsibility means divided tasks, not an absence of responsibility.

Internet Technology Context

The Internet is a packet-switched network of interconnected networks using the TCP/IP protocol suite. An IP address identifies an interface for routing packets. The Domain Name System (DNS) resolves human-readable names to IP addresses and other records. The World Wide Web is an Internet application: a browser uses a URL to identify a resource, HTTP or HTTPS to request it, and HTML plus related formats to represent the page.

Cloud services may be reached over the public Internet or private links; cloud computing and the Internet are therefore related but not synonyms. HTTPS protects a connection in transit, while cloud IAM determines whether the authenticated principal is authorized to use the requested resource.

Quick Review

• Five characteristics: on-demand self-service, broad network access, resource pooling, rapid elasticity and measured service.

• Service models: IaaS supplies virtual resources, PaaS supplies a managed application platform, and SaaS supplies the application.

• Deployments: public is provider-shared, private is dedicated to one organization, community is shared by organizations with common requirements, and hybrid coordinates distinct clouds.

• Shared responsibility: the provider/customer boundary changes by service model; customer data, identity and permitted configuration remain customer concerns.

• Internet/Web: the Internet is the TCP/IP network; the Web is an HTTP application running over it.

Tip

Exam Focus — Cloud answer

State all five essential characteristics, then separate service models from the public, private, community and hybrid deployment models. For a security question, draw the provider/customer boundary for the named service model and list IAM, encryption, isolation, logging, backup and compliance controls rather than claiming that either party secures everything.