Measure and compare CDNs with CloudPerf

In this tutorial we show you a practical application of CloudPerf, which is measuring and comparing CDNs. Since nowadays the CDN market is bigger than ever and equally diverse, we think it is very important to be able to compare and analyse CDN performance using an independent measurement platform before making any decision. This way you can see and compare by yourself using the same measurements across all providers of your interest.

It is important to take into account, that CloudPerf makes last-mile measurements, that is, right there where your users are. That is especially useful to contrast what CDNs or other providers say about their services and what your users are actually experiencing in real time.

Preparing your setup

    •  Make sure you have an account with CloudPerf, if not, you can get a free trial account on this link.
    • Make a list of all the URLs you would like to measure directly from your site. In this example we will use only one url to compare with four CDNs.
    • Make sure to compare a copy of the same file across all destinations.
    • Make sure all your URLs use the same protocol (http or https).
    • Set up your test domains for measuring your service with your desired CDN. You can get trial accounts on most CDNs. You can also setup a series of subdomains for testing many different CDNs with your content. So is linked to CDN-1, is for CDN-2 and so on.
    • Confirm that all your testing sites are using similar DNS configurations. CNAME cascading can affect measurements greatly and lead to unrealistic results.

In general, keep in mind that for testing purposes, it is best to configure all links as similarly as possible. Depending on the options each CDN gives, most of them can also provide test files for comparing their services. Some of these test files can also be found in the web. Nevertheless, we think that measurements are more meaningful if you test directly with your content. Especially if your site mixes cached and uncached content or if your site updates frequently, caching times become more relevant in the equation.

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* NEW * – CloudPerf now offers pre-configured links to popular CDNs for your convenience. Just click the drop-down menu on the “Create New Benchmark” button in the Dashboard and select “CDN Benchmark”. The benchmark editor will now include a list of checkboxes with popular CDNs so you can compare your own destinations with our current selection of CDN providers. We will be adding more and more CDNs with time!


Configuring CloudPerf

In this example, we will set up a comparison between one static object against 4 CDNs. Once you have everything prepared, log in to CloudPerf and you will be taken to the Dashboard. Click on “Create new Benchmark”. You will be taken to the benchmark editor.

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We name this benchmark “CDN Test”. We chose to measure a Static Object, but this example is also valid for using Page Load. Since we want to run the test for some hours, a 5 minute frequency is OK. For longer or permanent tests, you may want to measure less often. We select a number of countries in which we are interested to run the measurements.

CloudPerf uses a technique we call “Connection pre-warming”, in which two subsequent requests are made with every measurement: the first request will need DNS resolving and therefore will report longer measured times, while the second request has already a resolved DNS and will only report the connection time to the server. You have the option of including the DNS lookup time in your results.
This time we choose not to include DNS lookup times in our measurements, so we can observe in our results the “pure” connection time to our destinations.

For the first destination, we input the direct link to our origin server against which we will compare the CDNs’ performance. We chose to name it “Origin” and under URL we input naturally the direct link to the file we will test. Click on “Add new destination” and another line will appear. We name this and the subsequent lines with the CDN’s respective names, in this case, we simply numbered them. In the URL box we put either the address of the subdomain you previously configured to work with your site or any other link to a static object or web page to measure. For this post we compared one of our homepages with four real CDNs serving the same file.

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Click on “Save & Update” and voilà! We have configured our benchmark to measure our site and some CDNs simultaneously from thousands of different locations. We only have to wait now and take a look at the results after enough samples are taken.

Viewing Results

If enough time has passed, our first results will be ready. We simply log back into CloudPerf and once in the Dashboard view, we click our measurement’s name, which will take us to the results page.

By default we see first the latency measurement graph. The first thing we can notice from these results is that using any of those CDNs will make our website more responsive.

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If we remove the origin from the graph using the destinations buttons, since it is the slowest URL in this experiment, the graph will automatically zoom in and you will be able to observe and compare all four CDNs much more clearly. Please note the color change of the graph lines after modifying the destinations.

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You can use the results table below for having a first look at the measured latencies by country.
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If you wish to see the measurements over time in the countries of your interest only, you can select them using the Tests Running From field. You can also switch the graph between destinations and location using the Group By option.

It may be very intresting to compare results using different statistics. For example, if we select the 25th Percentile (faster connections) we can observe that CDN4 clearly outperforms the other three CDNs:
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while selecting the 95th Percentile (slower connections) our results show us longer latencies, but less clear differences between CDNs, although maintaining the general tendencies among them.
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Remember that CloudPerf is a very flexible tool and can be used for much more than measuring CDNs. Please take a look at our Quick User’s Guide and explore all the powerful options that CloudPerf has to offer!

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Google CDN Beta is here… and it’s already one of the fastest CDNs out there!

Some months ago, Google launched their Alpha program for their upcoming CDN service. We kept a close eye to their development and in the meanwhile, in NEXT 2016 Google has already announced the Beta phase of their CDN. We already discussed how this new product will fit in the broad palette of content distribution solutions Google has implemented. We have seen Google Global Cache, which is primarily aimed at speeding up their own services at ISP level, with more than 800 caches installed globally. CDN Interconnect is their partner program with third party providers like Cloudflare, Level3, Akamai, Highwinds, Fastly and Verizon, allowing them to use Google’s backbone network to transport content faster than ever from the source to practically anywhere where it is required, powering up CDNs not only with faster caching, but also enabling them to deliver rapidly changing content at top speeds.

Cloud CDN is Google’s own CDN solution for sites running in VMs inside Compute Engine. It is designed and implemented a bit differently from other CDNs, since it is meant to cache not only static content, but practically a whole site in more than 50 edge caches globally. It is a whole new take in the concept of CDNs, going way further than simply caching files, since it is directly integrated into their Load Balancing system and it literally means that a copy of your site will be running and serving from the closest location to your customers, with a single public IP address thanks to Anycast. In addition to HTTP/1.0 and 1.1 it also supports the new HTTP/2 protocol as well as free HTTPS, putting your site at the edge of current Web technology.


Using our tool CloudPerf, we were able to try out and see how well it performs compared to other CDN providers, including some of their Interconnect partners. We have four exact copies of our test VM in Google Compute Engine running in different locations worldwide. Since Cloud CDN is designed to run in front of a whole site, instead of only caching static objects, we designed a simple 100kB page to test this system at its best capabilities. CloudPerf uses a real instance of Chrome to load the whole page and measure the time it takes to visualize the content in a real web browser, measuring as always from the last mile, where real users are.

Please consider that CloudPerf‘s Page Load test, by using a real instance of Chrome requires a cold start of the browser instance and includes DNS resolution times. That means that at this moment the measurements using this method will have an overhead of +/-600ms added to the real measurement time. The relative measured times between all destinations are correct since all of them are made with the same probe, but the absolute measured times include the above mentioned overhead.

Now let’s see what happens with the 100kB Page Load test in a selection* of worldwide countries.

World Pageload graph
The average measured times by country and CDN can be seen in the following table:
World Pageload table
We can clearly see that Google Cloud CDN outperforms all other CDNs in loading a whole page in most countries. We can have a look at the special case of Japan, which shows the lowest measured times, by simply filtering results in CloudPerf.
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Going further, if we take a look at a selection of european countries**, we observe a similar situation only with Cloudfront, Level3 and Akamai coming a lot closer to Google’s performance.
PageLoad Europe

Now, in the USA the battle is fierce, although higher than Japan, the overall loading times of most CDNs are very close to each other and the general performance is really good, except for MaxCDN, which in our measurements got a little behind the rest, but still performing reasonably well in comparison to other regions. Nevertheless, it is evident that CDNs strive for top performance especially in the US market.
USA Pageload graph

How does Google achieve such top loading times practically everywhere? We think that this is precisely due to the fact that Google CDN is embedded in the Load Balancing system of Compute Engine and that means that you can configure your site to automatically replicate your VMs whenever it is necessary to a location closest to your users, meaning an overall higher response time and effectively shortening loading times.There is a very noticeable difference when we include into the equation the time it takes to load and resolve all objects of a page from a single location close to the user, as opposed to other CDNs where only traditionally cacheable content gets copied and the rest has to be retrieved from the origin.

PS: You can make your own comparisons and performance tests using CloudPerf.Sign up now!

* Australia, Brazil, France, Germany, India, Japan, Russia, Singapore, South Africa, Turkey, United Kingdom and United States

** France, Germany, Italy, Netherlands, Norway, Poland, Romania, Spain, Sweden and United Kingdom.