Cloud Computing Management

For high availability, Node Manager should run as a daemon or service on every machine that hosts Managed Servers. This allows remote start/stop and auto-restart capabilities. Running Node Manager only on the Admin Server machine (option B) defeats the purpose since Managed Servers typically run on different machines.

Virtualization is the foundational technology that enables cloud computing. It allows physical hardware to be partitioned into multiple virtual machines, enabling resource sharing, scalability, and the on-demand provisioning model that defines cloud services. Without virtualization, modern cloud computing would not exist.

Cloud computing provides services at three layers: Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). Since all three are valid service models provided in cloud computing, 'All of these' (E) is the correct answer. Individual options A, B, and C are each correct but incomplete.

Data confidentiality is the primary concern organizations have about cloud computing. While service provider dependency (B), performance issues (C), and virtualization (D) are relevant considerations, the security and privacy of sensitive data stored on third-party servers is the most significant barrier to cloud adoption, especially for enterprises.

All three statements accurately describe different aspects of WCF. Option A defines WCF's purpose as Microsoft's unified programming model, B describes its capabilities for secure and reliable solutions, and C explains its design philosophy for distributed computing.

AppFabric was a cloud middleware service for Windows Azure that provided caching and service bus capabilities. It was indeed a Windows Azure service, unlike Windows Server or Windows 7 features which are on-premise solutions. AppFabric helped developers build distributed applications more easily.

Cloud computing patterns encompass five key capabilities: Scale (elasticity), Multi Tenancy (resource sharing), Compute (processing power), Storage (data persistence), and Communications (networking and messaging). This comprehensive list covers all major cloud computing capabilities.

The primary variants of cloud computing deployment models are Public Cloud (shared infrastructure) and Private Cloud (dedicated infrastructure). While hybrid and community clouds exist, the question focuses on the two main variants. Option B correctly captures the primary distinction.

The Windows Azure platform is hosted and operated from Microsoft's own global network of data centers. This provides the physical infrastructure, security, and management for the Azure cloud services. It is not hosted in third-party, enterprise, or government data centers.

Private clouds can deliver all three primary cloud service models: Infrastructure as a Service (IaaS) provides virtualized computing resources, Platform as a Service (PaaS) offers application development platforms, and Software as a Service (SaaS) delivers applications over the network. Private clouds simply refer to the deployment model (dedicated infrastructure) rather than limiting the service types offered.

Amazon EC2 (Elastic Compute Cloud) is the quintessential IaaS offering - it provides raw virtual machines that users can configure with any operating system, software, and networking setup. Unlike PaaS (which abstracts the platform) or SaaS (which delivers complete applications), EC2 gives customers control at the infrastructure layer while AWS manages the physical hardware.

Salesforce (CRM), Facebook (social network), Skype (communication), and Purewire (security services) are all delivered as complete applications accessed over the internet - the defining characteristic of SaaS. Unlike IaaS (raw infrastructure) or PaaS (development platforms), these provide ready-to-use software where users interact with the application itself rather than managing any underlying infrastructure or platform.