Explanation
The Oracle Cloud Infrastructure Notifications service broadcasts messages to distributed components through a publish-subscribe pattern, delivering secure, highly reliable, low latency and durablemessages for applications hosted on Oracle Cloud Infrastructure and externally. Use Notifications to get notified when event rules are triggered or alarms are breached, or to directly publish a message.
Messages sent out as email by the Oracle Cloud Infrastructure Notifications service are processed and delivered through Oracle resources

Reference: https://www.oracle.com/cloud/storage/data-transfer.html

Explanation
Oracle Cloud Infrastructure Compute lets you provision and manage compute hosts, known as instances You can launch instances as needed to meet your compute and application requirements. After you launch an instance, you can access it securely from your computer, restart it, attach and detach volumes,and terminate it when you're done with it. Any changes made to the instance's local drives are lost when you terminate it. Any saved changes to volumes attached to the instance are retained.
Oracle Cloud Infrastructure offers both bare metal and virtual machine instances:
1) Bare Metal: A bare metal compute instance gives you dedicated physical server access for highest performance and strong isolation.
2) Virtual Machine: A virtual machine (VM) is an independent computing environment that runs on top of physical bare metal hardware. The virtualization makes it possible to run multiple VMs that are isolated from each other. VMs are ideal for running applications that do not require the performance and resources (CPU, memory, network bandwidth, storage) of an entire physical machine.
An Oracle Cloud Infrastructure VM compute instance runs on the same hardware as a bare metal instance, leveraging the same cloud-optimized hardware, firmware, software stack, and networking infrastructure.

Reference: https://docs.cloud.oracle.com/en-us/iaas/Content/Identity/Concepts/overview.htm#one

Explanation
The Oracle Cloud Infrastructure Domain Name System (DNS) service lets you create and manage your DNS zones. You can create zones, add records to zones, and allow Oracle Cloud Infrastructure's edge network to handle your domain's DNS queries.