What is a public cloud?
A public cloud is a cloud service offered to multiple customers by a cloud provider. The term "public cloud" is used to differentiate between the original cloud model of services accessed over the Internet and the private cloud model. Public clouds include SaaS, PaaS, and IaaS services.
Like all cloud services, a public cloud service runs on remote servers that a provider manages. Customers of that provider access those services over the Internet.
What is the difference between a public cloud and a private cloud?
A private cloud is a cloud service that is not shared with any other organization. The private cloud user has the cloud to themselves.
By contrast, a public cloud is a cloud service that shares computing services among different customers, even though each customer's data and applications running in the cloud remain hidden from other cloud customers.
A public cloud is like renting an apartment, while a private cloud is like renting a similarly sized house. The house is more private, but it also typically costs more to rent, and it's not the most efficient use of resources. Maintenance in the apartment is handled by the building supervisor, but it's harder to get a contractor out to fix the house (sometimes, the tenant may have to do it themselves).
There are hosted private clouds, which are offered by a third party cloud provider, and internal private clouds, which are managed and maintained by an organization internally.
What is multitenancy?
Because multiple organizations share a public cloud, multiple organizations will sometimes be using the same physical server at the same time. This is called multitenancy.
Multitenancy is when multiple customers of a cloud provider are accessing the same server. Data from two different companies could be stored on the same server, or processes from two different applications could be running on the same server.
What are the pros and cons of using a public cloud?
- Cost savings: Moving to a public cloud is a way for companies to cut down IT operations costs. Essentially, they are outsourcing these costs to a third party who can handle them more efficiently. Public clouds also typically cost less than private clouds, because the cloud provider is able to maximize their use of hardware and their profits by selling their services to multiple customers at once.
- Less server management: If an organization uses a public cloud, internal teams don't have to spend time managing servers – as they do for legacy on-premises data centers or for internal private clouds.
- Security: Many small and medium sized businesses may not have the resources to implement strong security measures. By using a public cloud service, they can outsource some aspects of cyber security to a larger provider with more resources.
- Security and compliance concerns: Multitenancy might be a concern for businesses that need to meet strict regulatory compliance standards. Multitenancy also comes with a very small risk of data leakage, which may be more risk than some businesses in specialized fields are willing to tolerate. (In fact, the risk is miniscule; most cloud providers follow extremely high security standards.) Finally, it can be difficult to deploy the same security policies both for an organization's internal resources and for a public cloud that is somewhat outside of an organization's control (especially during a cloud migration).
- Vendor lock-in: This is always a concern with cloud technology. An organization that uses the cloud will save money and become more flexible, but it can also end up reliant upon the cloud vendor's services – the virtual machines, storage, applications, and technologies they provide – in order to maintain their business operations.
What do 'multicloud' and 'hybrid cloud' mean?
Multicloud and hybrid cloud deployments both incorporate public clouds:
- Multicloud refers to the use of multiple public clouds concurrently.
- Hybrid cloud deployments combine one or more public clouds with a private cloud, or with on-premises infrastructure.
How does Cloudflare help organizations that use public clouds?
For Cloudflare customers, the Cloudflare network sits in front of public clouds for greater security and performance. Network traffic from end users is directed to the nearest Cloudflare data center, and the full Cloudflare product stack runs in every data center, reducing latency and filtering out malicious traffic. For those organizations that also want to incorporate an on-premises data center, a private cloud, or multiple public clouds, Cloudflare also supports hybrid cloud, multicloud, or any other type of infrastructure. Cloudflare also minimizes the risk of vendor lock-in by serving as a single control plane for multiple essential functions, including DNS, SSL/TLS encryption, DDoS protection, and CDN caching.