Explanation
Oracle Cloud Infrastructure is hosted in regions and availability domains. A region is a localized geographic area, and an availability domain is one or more data centers located within a region. A region is composed of one or more availability domains. Most Oracle Cloud Infrastructure resources are either region-specific, such as a virtual cloud network, or availability domain-specific, such as a compute instance. Traffic between availability domains and between regions is encrypted. Availability domains are isolated from each other, fault tolerant, and very unlikely to fail simultaneously. Because availability domains do not share infrastructure such as power or cooling, or the internal availability domain network, a failure at one availability domain within a region is unlikely to impact the availability of the others within the same region.
The availability domains within the same region are connected to each other by a low latency, high bandwidth network, which makes it possible for you to provide high-availability connectivity to the internet and on-premises, and to build replicated systems in multiple availability domains for both high-availability and disaster recovery.
Oracle is adding multiple cloud regions around the world to provide local access to cloud resources for our customers. To accomplish this quickly, we've chosen to launch regions in new geographies with one availability domain.
As regions require expansion, we have the option to add capacity to existing availability domains, to add additional availability domains to an existing region, or to build a new region. The expansion approach in a particular scenario is based on customer requirements as well as considerations of regional demand patterns and resource availability.
For any region with one availability domain, a second availability domain or region in the same country or geo-political area will be made available within a year to enable further options for disaster recovery that support customer requirements for data residency where they exist.

Explanation
The available purchase models are:
Pay As You Go (PAYG):Billed in arrears based on consumption. Recommended for organizations who are trying new services, rapid prototyping, or for elastic scaling.
Monthly Flex:Billed in advance with a 12-month minimum. Use monthly or forfeit that month's credits.Recommended for customers with predictable production workloads or large long-running applications, such as HR, payroll, analytics, and more.Monthly Flex maximizes cost reduction with predictable monthly spend, similar to your monthly phone plan. Delivers faster time to market by offering customers the choice of using any IaaS and PaaS services.
Oracle's current PaaS offering is "license-included PaaS." It includes:
* Compute and compute support
* Automation
* License entitlement and license support
Bring your own license
BYOL stands for "bring your own license." Previously, you could bring your own licenses to Oracle IaaS, but to get the benefits of PaaS automation, you couldn't leverage existing licenses. This has been changed. We're offering Oracle BYOL to PaaS, enabling our customers to leverage their investment in existing on-premises licenses in their journey to the cloud.
Oracle BYOL to PaaS includes:
* Compute and compute support
* Automation
* Customers bring their on-premises license entitlement and get license support via their existing on-premises support contract.
* As customers leverage their existing on-premises license entitlement, they can move to the cloud at a lower cost.

Explanation
There are 2 types of DB systems on virtual machines:
A 1-node VM DB system consists of one VM.
A 2-node VM DB system consists of two VMs clustered with RAC enabled.

ExplanationOracle Cloud Infrastructure File Storage service provides a durable, scalable, secure, enterprise-grade network file system. You can connect to a File Storage service file system from any bare metal, virtual machine, or container instance in your Virtual Cloud Network (VCN). You can also access a file system from outside the VCN using Oracle Cloud Infrastructure FastConnect and Internet Protocol security (IPSec) virtual private network (VPN).
Large Compute clusters of thousands of instances can use the File Storage service for high-performance shared storage. Storage provisioning is fully managed and automatic as your use scales from a single byte to exabytes without upfront provisioning.
The File Storage service supports the Network File System version 3.0 (NFSv3) protocol. The service supports the Network Lock Manager (NLM) protocol for file locking functionality.
Oracle Cloud Infrastructure File Storage employs 5-way replicated storage, located in different fault domains, to provide redundancy for resilient data protection. Data is protected with erasure encoding.
The File Storage service uses the "eventual overwrite" method of data eradication. Files are created in the file system with a unique encryption key. When you delete a single file, its associated encryption key is eradicated, making the file inaccessible. When you delete an entire file system, the file system is marked as inaccessible.
The service systematically traverses deleted files and file systems, frees all the used space, and eradicates all residual files.
Use the File Storage service when your application or workload includes big data and analytics, media processing, or content management, and you require Portable Operating System Interface (POSIX)-compliant file system access semantics and concurrently accessible storage. The File Storage service is designed to meet the needs of applications and users that need an enterprise file system across a wide range of use cases, including the following: