Will Your Customer Wait to be Served?

  • Customers expect speed and efficiency when it comes to content.
  • Sites using CDNs can deliver homepage content 26% faster than sites with no CDN present.

The Internet has been very successfully described as a “cloud.” Logos for companies offering cloud services often depict a big puffy singular cloud. When I think of the Internet as a cloud, I don’t think of soft puffy clouds, but of the clouds of the Seattle winter – a giant, all-encompassing cloud that connects sky and earth and everything in between. Since everything is connected, it is easy to visualize all the data coming together and flowing to customers.

In reality, this is not how the Internet works. While our data may not be hosted at our physical location, it does reside on servers that have discrete physical locations on the terrestrial earth. Where your servers are physically located has a direct impact on how long it takes for data to get from your server to your customers. And studies show customers don’t have the luxury of patience.

Science time

Let’s talk physics. (I promise it’ll be easy.) The “tubes” of the internet are primarily fiber optic cable, so your data is traveling at the speed of light (~200 million meters per second). At that speed, data can circumnavigate the earth five times per second. If your servers are in New York, it takes 23 ms for data to reach me in Seattle. Round-trip time (RTT) is 46 ms.

Every time I connect to your server, there are at least four connections that have to be made (if you are curious – these are: DNS lookup, TCP Handshake, TLS (security), and the initial HTTP request). Four round trips add up to 184 ms – before ANY data is sent! If I were in Sydney, the RTT to New York is 160 ms – so a connection setup from NYC takes over 600 ms!  If you add in mobile delivery, the latency is even higher, due to the technological effects of wireless networks.

Fast Content Delivery with CDN

If your data is traveling at the speed of light, how can we speed up the delivery of your data? This is where a Content Delivery Network (CDN) comes in. A CDN places all of your content on servers that are geographically distributed throughout the world.

Imagine you are using a CDN with your data (formerly only hosted in NYC), and the file is now mirrored in San Francisco. The round-trip time (RTT) for data to travel to Seattle is now just 13 ms. And the 4 RTTs to Seattle will occur in 52 ms. That’s 3.5x faster! And faster loading can result in an increase of repeat views, customer satisfaction, and sales.

Does CDN speed optimization hold true for the entire Internet? The HTTP Archive is a database of website performance stats for the top 200k desktop and 5k mobile websites. One measurement (only for desktop, unfortunately) is whether the main page HTML is hosted on a CDN. The results are recorded in Redwood City, CA using IE 9, and this data is from February 2014.

The important take-away? Sites with a CDN serving the content of the homepage deliver content 15-20% faster.

Charting CDN success

Presented below are the median values for the Time to First Bytes (TTFB) and the time it took for the website to start rendering (both measured in milliseconds).

CDN chart

As you can see, sites with a CDN serving the initial html of the homepage deliver the content 26% faster, and begin rendering content ~20% faster than those without.  Note: The “no CDN” data is not 100%. There are a number of sites with CDNs in this list, so in reality, your savings will be even better!

Pages also finish loading faster if there is a CDN present. The SpeedIndex is a measurement of how fast the page appears on the screen.  For sites with similar numbers of requests, those with at least the first page hosted on a CDN are generally 15-20% faster.


CDN chart

Delivering content as fast as you can

Getting your content to your customers as quickly as possible has been proven to be good for business. Tools like AT&T’s Application Resource Optimizer (ARO) help your developers figure out how they can make their code run faster and more efficiently. And, as the data shows, one simple way to get your content to your customers as quickly as possible across the all-connected cloud is to host your data on a CDN.

How might your business benefit from a CDN? Could faster connections be better for business?

Doug Sillars Principal Technical Architect AT&T About Doug