Content Delivery Networks (CDNs) have become essential for any business looking to improve website speed and reliability. By caching content on multiple servers across the globe, CDNs help reduce load times for users no matter where they’re located. But while CDNs are powerful, they don’t solve all performance issues and it’s essential to understand where they can fall short. In this post, we’ll look at some of the limitations of CDNs, explain why they’re still valuable, and share how Dotcom-Monitor can support your performance goals alongside a CDN.
General CDN drawbacks
While CDNs offer considerable benefits, there are also some general limitations to keep in mind:
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Not a Full Substitute for Site Optimization: A CDN can reduce load times by caching static content, but it doesn’t address website coding inefficiencies, large file sizes, or heavy plugins. These aspects are critical to page speed and require direct optimization at the site level.
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Higher Costs with Increased Traffic: CDNs often use a pay-as-you-go model, which can be cost-effective initially. However, as traffic scales up, these costs can increase significantly, especially for sites with a lot of data-intensive media. In these cases, the CDN can end up consuming a considerable part of your budget.
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Less Effective for Dynamic Content: CDNs work by caching content, so they’re most effective for static resources. However, dynamic content like personalized recommendations, real-time data, or frequently updated pages isn’t as easy to cache, which limits how much a CDN can improve load times for this type of content.
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Limited Control Over Caching Locations: While CDNs offer a network of global servers, the specifics of these locations and caching practices may be beyond your control. This means there may still be regions where certain users face delays or lower performance.
SSL Performance Issues
SSL is infamous for inherent performance issues. It requires additional and frequent round-trip transfers between the browser and the server at the elementary level. Here is an example, just to give you an idea of what performance issues to expect.
Suppose a TCP handshake took 95ms. Now, this is RTT (Round-Trip Time) between a server in New Jersey and test location in Los Angeles. SSL negotiations require at least two additional round-trips between the server and the browser. Now, if your CDN servers aren’t configured properly for SSL negotiations with various browsers, you are more likely to experience a delay in performance.
Performance Issues a CDN Can’t Help With
Adding CDN to your infrastructure guarantees enhanced performance and reliability. But specific performance issues need more than just a CDN, such as your own web application servers. With many web applications, you may still experience a lack of performance should you not implement certain resources and configurations.
Some of the other performance arenas where a CDN may not be able to resolve problems are the following:
Inadequate Hardware Resources
Your main application server is known as an origin server, from where CDN pulls and caches the data. Now, if your server has low resources and starts getting a spike in traffic, in this case, even the most decent CDN will not be able to do enough to improve your performance. You will need a faster server with ample resources to handle increased traffic.
Low resources, such as hard drive power, CPU power, and RAM, reduce the efficacy of your web application. Whenever you consider the integration of a CDN into your infrastructure, always ensure that your application server has sufficient resources to handle the traffic and data transferred to your CDN network.
Sluggish Network Resources
Whenever a CDN server pulls data from your main application server, the speed at which the content transfers depends on several factors, such as your network resources. Lack of network speeds to match the demands or to have low bandwidth from your sharing host both can hinder your performance by slowing down data transfer.
Bandwidth is an essential element to enable the transference of large content files across data centers on the CDN network from your network. Most ISPs offer proficient bandwidth for consumers. However, local networks hosting web applications must have adequate bandwidth installed to transfer large content files on local networks.
Third-Party Software
Although being dependent on applications is not a new concept to the developers, but most third-party software installations and additions must get tested for performance. Some issues can actually become the driving force behind affecting the entire web application performance. Performance issues may also arise from the installation of third-party tools on web servers.
In this instance, a CDN will not help to give you the answers you’re looking for. You will likely need to test any third-party software, tools, and dependencies in a simulated environment before installing them over your infrastructure, as well as in the production environment. On top of that, interaction and performance with software must be tested with your critical servers.
Cache Settings
Although your CDN edge server is responsible for caching and delivering content, your websites and applications also require configuration to cache static content. Static content may include CSS code, JavaScript, and HTML, which does not change frequently. As this content is static, you do not need to conduct a full lookup on your server to generate an appropriate server response.
In some scenarios, the administrators may have incompatible cache settings, which can mess up overall cache configurations. You can test these server responses post-deployment in staging or production environments.
Once you have configured these settings, you can always re-test your websites and applications. You can use tools, such as the Website Speed Tool from Dotcom-Monitor or other tools like Google PageSpeed Insights. Only with the correct CDN configuration and the right server resources will your website be able to perform efficiently irrespective of spikes in popularity and seasonal traffic.
Why Invest in a CDN at All?
Given these limitations, you may wonder why a CDN is still worth it. The answer lies in what a CDN does offer:
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Improved Load Times for Global Users: Despite the limitations, CDNs do an incredible job of reducing latency by distributing your content across many locations. Users around the world experience faster load times, leading to better engagement and lower bounce rates.
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Reduced Server Load: A CDN reduces the strain on your origin server by handling content delivery across its network. This makes it easier to manage traffic spikes and ensures more uptime during high-traffic periods.
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Enhanced Security: Many CDNs offer added security features, such as DDoS protection and Web Application Firewalls (WAFs), which help protect your site against malicious traffic.
A CDN may not solve every performance issue, but it significantly boosts the reliability and availability of your content.
A CDN Still Pays Off in the End
Despite their drawbacks, CDNs continue to be an essential component of a strong website performance strategy. They deliver tangible improvements in user experience, security, and reliability. But to get the most out of a CDN, it’s helpful to pair it with a monitoring solution like Dotcom-Monitor.
Dotcom-Monitor complements your CDN by offering real-time performance insights and synthetic monitoring, ensuring your CDN is delivering as expected and flagging any potential issues. Here’s why Dotcom-Monitor is the ideal partner to your CDN:
- Continuous Performance Monitoring: Dotcom-Monitor provides continuous visibility into your website’s performance from different locations worldwide. This allows you to identify areas where users might still experience lag and optimize accordingly.
- Detailed Reports on Downtime and Latency: Dotcom-Monitor can capture detailed reports on latency, load times, and overall uptime. This helps you see where the CDN is performing well and where additional adjustments may be needed.
- Enhanced Security Monitoring: Paired with a CDN’s security features, Dotcom-Monitor adds another layer of oversight by tracking potential threats and unusual traffic patterns. This provides peace of mind and a proactive approach to security.
In short, while a CDN tackles a lot of performance issues, pairing it with Dotcom-Monitor ensures you have a comprehensive view of your site’s health and performance across the globe. This combination of content delivery and robust monitoring makes sure you’re delivering the best possible experience for all your users.
