Explanation
Cost Analysis is an easy-to-use visualization tool to help you track and optimize your Oracle Cloud Infrastructure spending, allows you to generate charts, and download accurate, reliable tabular reports of aggregated cost data on your Oracle Cloud Infrastructure consumption. Use the tool for spot checks of spending trends and for generating reports

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 OracleCloud 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.
A fault domain is a grouping of hardware and infrastructure within an availability domain. Each availability domain contains three fault domains. Fault domains provide anti-affinity: they let you distribute your instances so that the instances are not on the same physical hardware within a single availability domain. A hardware failure or Computehardware maintenance event that affects one fault domain does not affect instances in other fault domains. In addition, the physical hardware in a fault domain has independent and redundant power supplies, which prevents a failure in the power supply hardware within one fault domain from affecting other fault domains.

This topic describes how to set up and manage a Network Address Translation (NAT) gateway. A NAT gateway gives cloud resources without public IP addresses access to the internet without exposing those resources to incoming internet connections. You can add a NAT gateway to your VCN to give instances in a private subnet access to the internet. Instances in a private subnet don't have public IP addresses.
With the NAT gateway, they can initiate connections to the internet and receive responses, but not receive inbound connections initiated from the internet. NAT gateways are highly available and support TCP, UDP, and ICMP ping traffic. Reference: https://docs.cloud.oracle.com/en- us/iaas/Content/Network/Tasks/NATgateway.htm?Highlight=NAT%20gateway

Reference:
https://www.youtube.com/watch?v=KKDLIjy2yJM&list=PLKCk3OyNwIzuHYigVbdtDOZOfChcotfj2&index
=7

Explanation
Oracle offers several different service level agreements as defined in this section (Service Level Agreements).Service level agreements range from least restrictive (data plane) to more restrictive (control plane) to most restrictive (performance).