The Basics of Computer Networks: Content Delivery Network (CDN)
This is a multi-part series on DevOps 101. Access the complete DevOps series by clicking HERE
Access the The Basics of Computer Networks: Network Virtualization (Previous post in Networking) by clicking HERE
A Content Delivery Network (CDN) is a network of servers that are distributed around the world. The purpose of a CDN is to deliver web content to users as quickly as possible, regardless of their location.
When a user requests a web page from a website that uses a CDN, the CDN will first check to see if the requested content is cached in one of its servers. If the content is cached, the CDN will deliver the content to the user from the nearest server. If the content is not cached, the CDN will fetch the content from the origin server and then cache it on one of its servers.
Working of a CDN
A CDN works by caching content on servers that are distributed around the world. When a user requests a web page from a website that uses a CDN, the CDN will first check to see if the requested content is cached in one of its servers. If the content is cached, the CDN will deliver the content to the user from the nearest server. If the content is not cached, the CDN will fetch the content from the origin server and then cache it on one of its servers.
The following are the key components of a CDN:
- Origin server: The origin server is the server that hosts the original content. The CDN will fetch content from the origin server when it is not cached on any of the CDN servers.
- Edge servers: The edge servers are the servers that are located in different parts of the world. The CDN will cache content on the edge servers so that it can be delivered to users from the nearest server.
- DNS servers: The DNS servers are used to resolve domain names to IP addresses. The CDN will use the DNS servers to route users to the nearest edge server.
Here are the steps on how a CDN works:
- A user requests a web page from a website that uses a CDN.
- The CDN checks to see if the requested content is cached on any of the edge servers.
- If the content is cached, the CDN delivers the content to the user from the nearest edge server.
- If the content is not cached, the CDN fetches the content from the origin server.
- The CDN caches the content on the nearest edge server.
- The CDN delivers the content to the user from the nearest edge server.
Benefits of a CDN
There are many benefits to using a CDN, including:
- Improved performance: A CDN can significantly improve the performance of a website by reducing the distance that content has to travel to reach users. This can lead to faster page load times, which can improve user satisfaction and reduce bounce rates.
- Increased availability: A CDN can help to improve the availability of a website by distributing content across multiple servers. This means that if one server goes down, the content can still be delivered from another server.
- Reduced bandwidth costs: A CDN can help to reduce bandwidth costs by caching content on servers that are closer to users. This means that less traffic will need to be sent to the origin server, which can save on bandwidth costs.
- Improved security: A CDN can help to improve the security of a website by providing DDoS protection and other security features.
- Scalability: A CDN can easily scale to meet the demands of a growing website. This means that you don’t have to worry about your website becoming slow or unavailable as it grows in popularity.
Here are some specific examples of how a CDN can benefit a website:
- A website with a lot of traffic from a specific region can use a CDN to cache content on servers in that region. This will help to improve the performance of the website for users in that region.
- A website that experiences spikes in traffic, such as during a marketing campaign, can use a CDN to help handle the increased load. This will help to prevent the website from becoming slow or unavailable during these spikes.
- A website that hosts large files, such as videos, can use a CDN to improve the performance of those files. This will help to reduce the amount of time it takes for users to download those files.
Types of CDNs
There are many different types of CDNs, but they can be broadly categorized into two main types:
- Pull CDNs: Pull CDNs are the most common type of CDN. With a pull CDN, the origin server sends content to the CDN servers, which then cache the content. When a user requests a page from the website, the CDN server will deliver the content from its cache.
- Push CDNs: Push CDNs are less common than pull CDNs. With a push CDN, the website owner pushes content to the CDN servers. The CDN servers then cache the content and deliver it to users when they request it.
In addition to these two main types, there are also a number of other types of CDNs, including:
- Peer-to-peer CDNs: Peer-to-peer CDNs use the resources of individual users’ computers to cache content. This can be a more cost-effective way to deliver content, but it can also be less reliable.
- In-house CDNs: In-house CDNs are CDNs that are owned and operated by the website owner. This can give the website owner more control over the CDN, but it can also be more expensive.
- Hybrid CDNs: Hybrid CDNs combine the features of pull CDNs and push CDNs. This can provide the best of both worlds, but it can also be more complex to set up and manage.
The type of CDN that is best for a particular website will depend on a number of factors, including the size of the website, the amount of traffic it receives, and the budget.
Here is a table that summarizes the different types of CDNs:
| Type of CDN | Description |
|---|---|
| Pull CDN | The origin server sends content to the CDN servers, which then cache the content. When a user requests a page from the website, the CDN server will deliver the content from its cache. |
| Push CDN | The website owner pushes content to the CDN servers. The CDN servers then cache the content and deliver it to users when they request it. |
| Peer-to-peer CDN | Uses the resources of individual users’ computers to cache content. This can be a more cost-effective way to deliver content, but it can also be less reliable. |
| In-house CDN | Owned and operated by the website owner. This can give the website owner more control over the CDN, but it can also be more expensive. |
| Hybrid CDN | Combines the features of pull CDNs and push CDNs. This can provide the best of both worlds, but it can also be more complex to set up and manage. |
Popular CDN Providers
| CDN Provider | Type | Cost |
|---|---|---|
| Akamai | Pull | Pay-as-you-go or subscription |
| Cloudflare | Pull | Free, pay-as-you-go, or subscription |
| Incapsula | Pull | Pay-as-you-go or subscription |
| KeyCDN | Pull | Pay-as-you-go or subscription |
| MaxCDN | Pull | Pay-as-you-go or subscription |
| StackPath | Pull | Pay-as-you-go or subscription |
| CDN77 | Pull | Pay-as-you-go or subscription |
The cost of a CDN will vary depending on the provider, the features you need, and the amount of traffic you receive. For example, Akamai’s pricing starts at $0.09 per GB, while Cloudflare’s pricing starts at $0 per month for the free plan.
Advantages and Disadvantages of a CDN
Here are some advantages and disadvantages of using a CDN:
Advantages:
- Improved performance: A CDN can significantly improve the performance of a website by reducing the distance that content has to travel to reach users. This can lead to faster page load times, which can improve user satisfaction and reduce bounce rates.
- Increased availability: A CDN can help to improve the availability of a website by distributing content across multiple servers. This means that if one server goes down, the content can still be delivered from another server.
- Reduced bandwidth costs: A CDN can help to reduce bandwidth costs by caching content on servers that are closer to users. This means that less traffic will need to be sent to the origin server, which can save on bandwidth costs.
- Improved security: A CDN can help to improve the security of a website by providing DDoS protection and other security features.
- Scalability: A CDN can easily scale to meet the demands of a growing website. This means that you don’t have to worry about your website becoming slow or unavailable as it grows in popularity.
Disadvantages:
- Cost: CDNs can be expensive, especially for large websites with a lot of traffic.
- Complexity: CDNs can be complex to set up and manage.
- Security: CDNs can be a target for DDoS attacks.
- Latency: In some cases, using a CDN can actually increase latency. This is because the content has to travel further to reach the user.
Do you Need a CDN?
Whether or not you need a CDN depends on a number of factors, including the size of your website, the amount of traffic it receives, and your budget.
Here are some things to consider when deciding whether or not you need a CDN:
- Size of your website: If you have a small website with low traffic, then you may not need a CDN. However, if you have a large website with high traffic, then a CDN can help to improve the performance of your website.
- Amount of traffic your website receives: If your website receives a lot of traffic from a specific region, then you may want to consider using a CDN that has servers in that region. This will help to improve the performance of your website for users in that region.
- Your budget: CDNs can be expensive, so you need to make sure that you can afford one. However, there are also some free CDN providers available, so you may be able to find one that fits your budget.
More great stuff related to networking coming soon! Stay tuned and share and subscribe for more!
Access the The Basics of Computer Networks: Network Virtualization (Previous post in Networking) by clicking HERE
This is a multi-part series on DevOps 101. Access the complete DevOps series by clicking HERE
