Selecting the Right Content Delivery Network (CDN) Provider

A content delivery network (CDN) helps to provide a complete web experience for site visitors. However, the right CDN provider needs to be selected to ensure this is the case. Providers of this service are able to ensure a better and faster experience for visitors by serving static assets, and additional services are provided as well. This includes site acceleration and more. How will a CDN provider benefit the business? What should a business consider when choosing a provider for their organization? What factors need to be taken into account as this selection is made? 

The Benefits of Using a CDN Provider

Content delivery network providers maintain larger network pipes along with numerous servers across the globe. In addition, they have vast network peering capabilities along with teams that focus on optimizing their stacks. The infrastructure is constantly monitored to handle increases in traffic as well. 

As a result, a CDN leverages economies of scale to provide clients with faster, better, and more cost-effective service that outpaces anything the business could achieve on its own. One thing needs to be remembered, however. Some CDN providers do this better than others and in a more efficient manner. This is why comparing the various options is so important. 

Basic Qualifications to Look For

When comparing content delivery network providers, certain basic qualifications should be considered essential. Any provider that does not meet these requirements should be removed from the list of potential companies to partner with. This includes an origin that is faster than what the company currently maintains and a provider that can deliver files of all sizes. 

In addition,  the provider needs to reduce the latency to fetch all page items as this minimizes the geographical impact. Once those providers have been identified that possess these basic qualifications, what should a business be looking for when making the selection? 

Network Size

Learn the size of the CDN service provider’s network. The largest CDN maintains more than 240,000 servers in its network. Other providers maintain more than 100,000 servers. The number of servers plays a role in the client’s ability to provide fast and reliable content. As the number of servers increases, buffering decreases. It becomes easier to scale to the client’s needs and redundancy improves. 

However, geographical distribution also needs to be factored in when comparing CDN providers. The United States and Europe have countless data centers, which helps to ensure good coverage in these areas. In contrast, Asia, the Middle East, Africa, and South America have limited coverage thanks to a much smaller number of data centers. The key is to find a provider that offers excellent coverage in these areas and more. 

DNS Time

Domain name system lookup time affects the performance of a site. This is the amount of time the domain lookup takes to occur as the browser retrieves the resource. To calculate the time, take domainLookupStart and subtract it from the domainLookupEnd in the navigation timing API.

The domain name is mapped to an IP address in order to be found. The lookup is nothing more than a request to a separate server asking the IP address for that domain name. This process can lead to a significant delay in rendering the webpage for the visitor and lead to a negative user experience. This depends in part on the complexity of the DNS setup. Faster wait times are often offset by slower response times in terms of the DNS.   

One thing to be aware of when comparing providers in this area is where the test occurs. DNS performance tends to be better for those who are close to the machine when the test is run. End users don’t have this proximity and this can affect DNS performance. Be sure to ask about DNS performance for the end user to obtain accurate information regarding this aspect. 

The Time to Connect

Network connectivity needs to be explored at this time to ensure it meets your needs as well as those of users. The same is true of packet loss and latency. One thing to investigate is the connect time during peak hours. Furthermore, make certain you are routed to the correct network peering. Users should not have to go through multiple backbone networks simply because the CDN lacks a direct peering with their ISP. 

Wait Time

Content needs to be hot on the edge to ensure it gets to site visitors in a timely manner. Furthermore, the wait time needs to be considered to determine if capacity issues may arise or the CDN or Origin server has configuration problems. 

Content delivery networks deliver different performance when the asset is hot, as popular items need to reach visitors faster. Items in memory are provided to the user in less time. However, if the content must hit a spinning disk, the time needed to reach the user significantly increases. This is why solid-state drives are the preferred choice when selecting a CDN provider.

Solid-state drives allow the provider to fetch cached items rapidly and handle more requests per second. Users then obtain the content more rapidly. 


Throughput differs based on the file size. When selecting a CDN service provider, keep this in mind. Conduct multiple tests to ensure the throughput remains higher than the origin regardless of the file size. 


Traceroutes need to be run from the location where the monitoring occurs. This helps to ensure you are mapped to the correct location. Commercial geo-mapping databases are common among CDNs. Sadly, the data used by the IP could be incorrect. If a CDN sends a request to Europe when the home connection is located in San Francisco, there is a disconnect somewhere. This needs to be known right away.


While the choice of CDN provider should never be made based solely on the price, this element does need to be factored into the decision-making process. Pricing should always be transparent and affordable. 

Businesses need to consider the two most popular pricing models when selecting who to work with. Custom negotiated contracts are the first pricing option. The provider looks at the client’s bandwidth and needs in terms of features and prices the service accordingly. However, the only way to know how much you will pay is to sign up with the company. 

The other option is based on how many gigabytes you use each month. As volume rises, the price typically decreases. Be aware that prices tend to vary by region. Amazon CloudFront is one provider that makes use of this model and gets great reviews, so be sure to check it out. 

Customer Support

Customer support is of great importance when it comes to a CDN. The support team should be available around the clock and provide knowledgeable and responsive support. First-time users often need assistance with setting up the CDN, as technical issues can lead to numerous problems that often don’t appear until an important broadcast is in progress. By having assistance during the installation of the CDN, this becomes less of a concern. 

Look for an in-house support team as opposed to one located in a call center. The team should consist of experts in the industry rather than general knowledge workers. Furthermore, phone support should be an option as there are times when email and chat simply aren’t fast enough to handle the issue being experienced and time is of the essence. 

Additional Factors

CDN providers typically offer clients access to a control panel. When comparing providers, be sure to check the cache hit/miss ratio. The goal is to determine how often visitors return to the origin. When a good architecture is in place, this shouldn’t happen very often. 

Furthermore, be sure to learn what happens when content is not present on an edge server. How long will it take to have the file loaded to the edge, and how long does it take to purge a file? In addition, ask the amount of time needed before a Cname becomes active. 

The handling of public name resolvers by the CDN needs to be addressed. This includes big names such as Google. As these companies handle more of the DNS traffic today, they can have an effect on the geo-load balancing algorithms of some CDNs.

Finally, are the CDN metrics consistent? Never look at only the averages. Great performance is affected by many factors, and CDN users need to recognize reliability and speed are both of importance. 

The selected content delivery network should improve your company’s performance in those markets where a physical server is not present and bring about an increase in revenue. Furthermore, it should offload static files to more servers to provide more bandwidth and personnel to handle other important issues. 

This network needs to help you handle seasonal traffic while addressing any DDOS attacks. Additionally, the provider should remain in communication with you at all times and provide a way for you to monitor their performance versus the origin. When a partnership like this is established, all parties benefit, including your customer base.

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