Different types of compute instances available in OCI:
- General purpose
- Compute optimized
- Memory optimized
- Accelerated computing
- Bare metal
Different types of storage available in OCI:
- Block storage
- Object storage
- File storage
- Archive storage
Different types of networking resources available in OCI:
- Virtual cloud networks (VCNs)
- Subnets
- Security lists
- Route tables
- Gateways
- Load balancers
Different types of databases available in OCI:
- Autonomous Database
- Database Service for Oracle Database
- Database Service for MySQL
- Database Service for PostgreSQL
- Database Service for NoSQL
Different types of analytics and AI services available in OCI:
- Analytics Cloud
- AI Platform
- Data Science Workbench
- Data Catalog
- Databricks in OCI
Different types of app development services available in OCI:
- Container Engine for Kubernetes (OKE)
- Cloud Native Applications Platform (CNAP)
- Functions
- API Gateway
- Service Mesh
- Mobile Backend as a Service (MBaaS)
Different types of security and compliance services available in OCI:
- Identity and Access Management (IAM)
- Key Management
- Security Zones
- Security Audit and Monitoring
- Data Governance
- Compliance
Different types of identity and access management services available in OCI:
- Identity and Access Management (IAM)
- Identity Cloud Service (IDCS)
- Unified Directory
- Access Management
- Identity Analyzer
Different types of observability and management services available in OCI:
- Monitoring
- Logging
- Analytics
- Notifications
- Cost Management
- Resource Manager
Different types of hybrid offerings available in OCI:
- Dedicated Region Cloud@Customer
- Managed Cloud@Customer
- Oracle Cloud VMware Engine
- Oracle Cloud Exadata Cloud Service
- Oracle Cloud Infrastructure FastConnect
A boot volume is a type of block volume that is used to boot a compute instance. It contains the operating system and all of the files required to start the instance. A block volume is a general-purpose storage device that can be used to store any type of data.
Boot volumes are typically smaller than block volumes, as they only need to contain the operating system and boot files. They are also typically configured to be more performant than block volumes, as they need to be able to quickly read and write data during the boot process.
Block volumes can be of any size and can be used to store any type of data, including operating systems, databases, applications, and user files. They are typically less expensive than boot volumes, but they may not be as performant.
Use cases for boot volumes:
- Booting a compute instance with an operating system
- Creating a bootable image for a compute instance
- Recovering a compute instance from a backup
Use cases for block volumes:
- Storing an operating system for a compute instance
- Storing data for a database or application
- Storing user files
- Creating a snapshot of a volume for backup or recovery
Example:
You can use a boot volume to install an operating system on a compute instance. Once the operating system is installed, you can use the boot volume to boot the instance. You can also use a boot volume to create a bootable image for a compute instance. This can be useful for quickly deploying multiple instances with the same operating system and configuration.
You can use a block volume to store data for a database or application. You can also use a block volume to store user files. Block volumes can be attached to multiple compute instances, so you can share data between instances. You can also create a snapshot of a block volume for backup or recovery.
A public IP address is a unique IP address that is assigned to your network router by your internet service provider (ISP). It is used to identify your router and your devices on the internet.
A private IP address is a unique address that is assigned to a device on a local network. It is used to identify the device within that network.
Use cases for public IP addresses:
- Hosting a website or web server
- Playing online games
- Using remote desktop software to access a computer on your home network from outside of your home
Use cases for private IP addresses:
- Connecting to a printer on a local network
- Sharing files between devices on a local network
- Playing multiplayer games on a local network
Example:
When you visit a website, your computer sends a request to the website's server. The server then sends back the website's content to your computer. In order for the server to know where to send the website's content, it needs to know your computer's IP address.
If your computer has a public IP address, the server can send the website's content directly to your computer. However, if your computer has a private IP address, the server will not be able to send the website's content directly to your computer. Instead, the server will send the website's content to your router. Your router will then forward the website's content to your computer.
This process is called network address translation (NAT). NAT is used to allow multiple devices on a local network to share a single public IP address.
differences between NAT gateways and load balancers:
NAT gateway is a managed network service that allows instances in a private subnet to access the internet. It does this by translating the private IP addresses of the instances to a single public IP address. This allows the instances to send and receive traffic from the internet, even though they do not have their own public IP addresses.
A load balancer is a device or software that distributes traffic across multiple servers. This can help to improve performance, reliability, and scalability. Load balancers can be used to distribute traffic between web servers, application servers, and database servers.
Use cases for NAT gateways:
- Allowing instances in a private subnet to access the internet
- Providing internet access to devices on a local network
Use cases for load balancers:
- Distributing traffic across multiple web servers
- Distributing traffic across multiple application servers
- Distributing traffic across multiple database servers
- Improving performance, reliability, and scalability of applications
Example:
A company has a website that is hosted on two web servers in a private subnet. The company wants to allow users to access the website from the internet. The company can use a NAT gateway to translate the private IP addresses of the web servers to a single public IP address. This will allow users to access the website by visiting the public IP address in a web browser.
The company could also use a load balancer to distribute traffic between the two web servers. This would help to improve performance and reliability. If one web server goes down, the load balancer will continue to distribute traffic to the other web server.
Conclusion:
NAT gateways and load balancers are both network devices that can be used to improve the performance, reliability, and scalability of applications. However, they have different purposes. NAT gateways are used to allow instances in a private subnet to access the internet, while load balancers are used to distribute traffic across multiple servers
database instance and a database cluster
| eature | Database Instance | Database Cluster |
|---|---|---|
| Definition | A single running instance of a DBMS | A group of database instances that work together as a single system |
| Purpose | To store, manage, and access data | To improve performance, scalability, and high availability |
| Scalability | Limited to the resources of a single server | Can be scaled up or down by adding or removing database instances |
| Availability | Can be unavailable if the server fails | Can remain available even if one or more database instances fail |
some examples of database clusters:
- A cluster of web servers that use a database to store user data
- A cluster of database servers that support a large online transaction processing (OLTP) system
- A cluster of database servers that store and analyze big data
A subnet is a subdivision of a VCN. Subnets are used to organize your resources within a VCN and to control network traffic between them. You can create multiple subnets in a VCN, each with its own range of IP addresses.
differences between VCNs and subnets:
| Feature | VCN | Subnet |
|---|---|---|
| Definition | A software-defined network that you create and manage in OCI | A subdivision of a VCN |
| Purpose | To isolate your resources from other VCNs and the public internet | To organize your resources within a VCN and to control network traffic between them |
| Size | A VCN can have up to 100 subnets | A subnet can have up to 4 billion IP addresses |
| Scope | A VCN is global to a region | A subnet is regional |
security list and a network access control list (NACL)?
A security list and a network access control list (NACL) are both firewall-like features that can be used to control traffic in and out of a network. However, there are some key differences between the two.
Scope
- A security list is associated with an instance, while a NACL is associated with a subnet. This means that a security list controls traffic to and from a specific instance, while a NACL controls traffic to and from all instances in a subnet.
Rules
- Security list rules can be used to allow or deny traffic based on the source IP address, destination IP address, port number, and protocol. NACL rules can also be used to allow or deny traffic based on the same criteria, but they can also be used to block specific IP addresses or ports.
Statefulness
- Security lists are stateful, meaning that they keep track of the state of connections and allow traffic in both directions for established connections. NACLs are stateless, meaning that they only evaluate traffic based on the individual packets, not the state of the connection.
Use cases
- Security lists are typically used to control traffic to and from specific instances, such as web servers or database servers. NACLs are typically used to control traffic to and from all instances in a subnet, such as a subnet that contains public-facing web servers.
What is the difference between a database role and a database user?
A database role is a logical grouping of permissions that can be assigned to database users. A database user is an individual user account that can be used to access a database.
Roles can be used to simplify permission management by assigning a single role to a group of users with similar needs. For example, you could create a role for developers that gives them permission to create and modify database objects, and a role for administrators that gives them permission to manage all aspects of the database.
Users can be assigned to multiple roles, and the permissions of all roles assigned to a user are combined. For example, a user who is assigned to both the developers role and the administrators role would have all of the permissions granted to both roles.
What is the difference between a database snapshot and a database backup?
A database snapshot is a point-in-time copy of a database. A database backup is a copy of the database that is typically used to recover from data loss or corruption.
Snapshots can be used to create test environments, to back up databases before making changes, or to restore databases to a previous point in time. Snapshots can be created quickly and easily, and they can be used to restore databases to their previous state just as quickly.
Backups are typically created on a regular schedule, such as daily or weekly. They can be stored on-premises or in the cloud. Backups are used to recover from data loss or corruption, such as if a database is accidentally deleted or corrupted.
What is the difference between a database instance resize and a database instance move?
A database instance resize is the process of changing the size of a database instance. This can be done to increase or decrease the resources allocated to the instance.
A database instance move is the process of moving a database instance to a different physical or virtual machine. This can be done for a variety of reasons, such as to improve performance or to migrate the instance to a different region.
What is the difference between a load balancer and a web application firewall (WAF)?
A load balancer distributes traffic across multiple servers. This can be used to improve performance and scalability, and to ensure that applications remain available even if one server fails.
A web application firewall (WAF) protects web applications from attacks. WAFs can be used to block common web attacks, such as SQL injection and cross-site scripting.
Load balancers and WAFs can be used together to improve the performance, scalability, and security of web applications.
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