CDN Adds Performance & Disaster Recovery

Content Delivery Network

CDNs don't just speed up your site. With the right setup, you can add security, disaster recovery and rollover during peak traffic spikes throughout the work week. With proper understanding of a CDN, you can add better delivery performance and reliability to your site's customers.

A content delivery network is one of the most important tools of any webmaster with a large and diverse user base. It works by caching your content on servers around the world so users may quickly access content without latency issues. While most CDN subscribers may be thinking about the speed of their website, there are a few niche benefits as a bonus.

How a CDN Delivers Traffic to Your Users

With traditional hosting, you lease server space and upload your website files to the server's storage. Whether you have shared hosting or a dedicated server, the host's equipment is always in one location. Higher end dedicated servers speed up server processing, but it doesn't address the issue of distance between the origin server and the user accessing the website. The “origin server” is a CDN term given to the hosting server that houses your website content.

Although data traverses the internet at the speed of light, distance still affects performance. Users must send requests from their computers and wait for these requests to reach the server. The server then sends data back to the user at the same speed and distance. Users see the wait times for data to download as “lag” or performance issues from your site. You can't control the user's bandwidth or the distance between these users and your origin server, but you can bring servers closer to users in the form of “edge servers” hosted by a CDN.

CDNs lease space in data centers across the globe. They call these locations “point of presence (PoP)” data centers. When you sign up to a CDN service, you should identify their PoPs to find out if they have a data center located in close proximity to a majority of your traffic. If you service mostly people in the US, then most CDNs have several PoPs across the US. Most CDNs have dozens of locations across the globe, but you should still verify that your chosen CDN has a data center close to your users.

With a CDN closer to users, now any traffic sent to your website is instead sent to the CDN's edge servers. These edge servers have cached content from your origin server, so not only do you have a boost in speed due to having a closer location to the user, but content is served from cache, which makes processing requests much faster. Cached content is processed and sent from server memory, which is much faster than distributing content from a hard drive.

What Happens When You Update Content?

A CDN edge server caches content, but you then need it to pull the latest data when your data changes. The CDN server polls your origin server for changes, so cached content is kept up-to-date. When you update content, every edge server updates its cache, so the most traffic you could see on your origin server comes from CDN updates. One benefit of a CDN is that you reduce the amount of traffic on your hosting server, which then saves you money in hosting fees.

The biggest benefit to a CDN is that large amounts of data are sent to edge servers where users can download them in cache. Gaming developers and any software company that distributes large files over the internet can benefit from these servers. Traditionally, a server for a gaming update would slow down considerably on patch day. Several gigabytes would be downloaded by gaming users all at once. With a CDN, you distribute these downloads across data centers and edge servers, and users download from the closest location.

Any updated content is replicated to your CDN's data center, so you don't need to worry about updates. You upload changes to the origin server and the CDN servers take care of the rest.

How a CDN Can Help with Cyber Security, Disaster Recovery and SEO

Your CDN can stop DDoS attacks from harming your site's performance when combined with the right firewall and intrusion detection system. DDoS attacks launch with no warning, so monitoring is needed to stop it before it exhausts server resources. With a CDN, you no longer need to worry about floods of traffic at your origin server without the right defenses.

Protecting Against DDOS Attacks or Spam Bots

In 2018 alone, several large companies were hit with debilitating denial of service (DDOS) attacks in order to interrupt their businesses. This included a record-setting 1.35 Tbps against Github. For smaller websites, you have no match against amateur zombie networks that sap up a few Gbps of bandwidth.

CDN providers like Cloudflare will have an “under attack” setting so those suspicious users will have to complete a captcha for each page request. For legitimate users, it will be trivial to solve the captcha while bots will be halted before causing harm.

Circumventing National Censorship

A user may use a website cache plugin or program to download content straight from your CDN server without resolving your domain name. This allows the user to completely bypass government firewalls that block websites at the DNS level. Of course, this becomes harder if they begin blocking IP address ranges.

Since most of the biggest pages on the internet make use of the same CDN servers, governments avoid blocking CDN IP addresses. As long as the connection is encrypted via SSL, your users from such countries will have a way to access your content.

Disaster Recovery

Help with disaster recovery is one of the most significant side benefits for an SRE. Suppose a major ISP router fails and users can't access your site. You have no control over a failed ISP router, so you must wait until the ISP is able to fix it. The ISP might reroute traffic, but even rerouting traffic kills performance.

With a CDN, if one router or data center fails, users are rerouted to the next closest edge server within the network. This could be a location that is still within 1,000 miles to your users’ location, so they see no difference in performance. Instead of having a slow website, your users see no changes and continue downloading content as if they are still connected to the original data center.

Rollover is common with CDNs when a data center fails, so you add disaster recovery to your infrastructure with just a few extra dollars a month. If you rely on your site for revenue, then having a CDN can add numerous disaster recovery benefits without worrying about a crashed server.

Search Engine Optimization

While keywords, fulfilling user intent and backlinks are the main determining factors in Google search rankings, site load speeds are also considered. If your website is overloaded, located far away, or simply not properly optimized at the operating system level, Google may see its slow load speed as a hindrance.

A CDN will help with caching the most recent revision of your website so that the Google bot will see the freshest content at the fastest speed possible. Some services will purge redundant content, which aids with concealing duplicate content issues from Google.

Whether your goal is faster performance or disaster recovery for a critical site, a CDN can benefit you more than traditional hosting. CDNs have locations around the globe, so even a simple change can speed up your website. These changes can make a substantial impact and should be a part of any website, mobile application, or online community. You will benefit from having a CDN by optimizing your site for search engines, web security, and increasing your international reach.