Francesco Altomare
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DNS: HTTP and CDNs #3

My Dear Reader,

Welcome back to the third and last Article (for the time being) on our DNS Mini Series; in our Previous Posts “DNS: The Basics #1” and “DNS: Intermediate Aspects #2” we covered an Introduction to DNS as a Protocol and explored some Intermediate Aspects of it, both as pertaining to your DNS Technical Operations and the Business most salient points for having a properly configured, robust, resilient, available, performant Infrastructure. Today we’ll take on with Business remarks and bridge DNS to its more famous brother Protocol HTTP, which is mostly (but not only) what CDNs are about. Let’s dive into it!

 

Welcome to the speediest WWW ever! Everything speedy begins by a speedy DNS

A.k.a. “how a slow DNS will kill your Online Business”. Let us feed you some numbers and facts before we proceed (food for thoughts):

  • Google found that a 500ms slowdown equals 20% decrease in ad revenue.
  • Microsoft Bing found that a 2-seconds slowdown means a 2.5% decrease in queries and overall clicks.
  • Amazon finds a 100ms slowdown – one tenth of a second! – can mean a 1% decrease in revenue.
  • Yahoo! found that a 400ms improvement in load time translated to a 9% increase in traffic.
  • Mozilla mapped a 2.2s improvement to 60 million additional Firefox downloads.
  • 27% of Users say that visiting a slow site makes them more likely to visit a competitor.

As if it weren’t enough, Google has announced that they are actively looking at how fast a page loads in determining organic search rankings. It has been well documented that landing page loading time has been a factor in Quality Score, a measurement for determining Ad placement within Google’s AdWords network. However, this is the first time Google has announced that they are actively looking at how fast a page loads in determining organic search rankings.
Why is that? “Elementary, my dear Watson!” Google has stated that their overarching goal is to improve User satisfaction and experience with the Internet. With their search algorithm, they look to promote sites that have the most relevant information and provide the best perceived value and User experience. One important way to improve the user experience – as we have established earlier – is by improving a site’s loading time.
Of course, one important way to improve a site’s loading time – as we have established earlier also – is by fine tuning your DNS Performance (not to even mention availability), which is the first ring of the Delivery chain.
Slow DNS resolution kills your traffic and SEO under normal conditions, but if you are in the Online Advertisement space as a Business, the situation can be far worse. Online Ads have to load up fast – for an End User to be tempted to click them and bring you money – and therefore have to be resolved even faster than a news article page. Failure to do so, means no clicks, it’s as simple as that.
All these facts lead to only one conclusion – you need a thundering fast DNS.

Can we do with an “in-house” DNS?

We touched this topic in our previous Post already, but let’s speculate on it once more: if you think you can setup DNS “in-house” you are not alone. Many have successfully done it. If your Customers are located in your geographic area you may not need to take the hassle of going for a serious DNS Service and / or CDN in the first place. However, an “in-house” or geographically localized DNS infrastructure won’t help you scale Worldwide, especially not in the second biggest market place on earth – China.
We will touch China more specifically in a dedicated Post as we move forward, but know that although it’s poised to be Planet Earth’s #1 Economy by 2016, Chinese Networks are troublesome to say the least and subject to the Chinese Government and Great Firewall. You aren’t going to get in there and profit of it without proper Infrastructure, Licenses and Performance, my Dear Reader.

Should we then buy a premium DNS Service?

When your Customers are dispersed all over the Globe, you should as a least consider buying a Premium DNS Service, even more so if you care about your HTTP Delivery via a Content Delivery Network. DNS is part of the game, my Dear Reader, for when you link your assets to a CDN an End User still has to follow the DNS resolution for enjoying your HTTP speedy lanes.
How does the linking to a CDN happen on a DNS level? It happens by means of the DNS CNAME Record.
CNAME is the magic DNS Record pointing your Website to a CDN, at least with most CDN Providers, and the Record itself looks like below:

www.mywebsite.com IN CNAME www.mywebsite.com.samplecdn.com

Your DNS serves the End User above Record pointing to a Hostname maintained by a CDN, and the CDN of your choice then handles all further DNS Resolutions from its own Hostname onwards. Only then comes HTTP into play, and if above Record takes ages to be served back to your End User there’s very little the CDN can do to improve your Delivery, whether you like it or not my dear Reader.

More Advanced DNS Products

Most Businesses who care about Performance already have some joint Premium DNS + CDN Solution today, and the old-fashioned are following after a soar lesson by not doing this up to now. The “Avant-garde” is actually going – or has actually gone already – for even more Advanced Solutions, both on a DNS and HTTP (CDN) level. Concepts like Load Balancing or Multi-CDN Delivery, topics we touched in one of our previous Posts are all the more important and make all the more sense now.
We hope that we’ve made to point that access to your Website has to be quick and fast across all Geographies; a single Content Delivery Network, though, may not be able to service all parts of the Globe in a performant way at all times and in all Internetworks.
We will repeat that to death, “all Hardware is bound to fail” and “all Networks are bound to peer”! And what is a CDN if not Hardware connected via Network Peerings Worldwide? We can hear you moaning, “I am happy with one CDN!” and we agree that one CDN is enough to improve on your Origin Infrastructure’s raw Worldwide Performance. Then again, we don’t expect you to be an Avant-garde kind of Reader or Business, but rest assured that many others are. Curiously enough, it’s the biggest and most successful Brands on earth often falling into this Category and we work with many of them.
We and our Customers hear the Zeitgeist whispering, and try to anticipate it in an endless struggle for the most Advanced and “next-gen” (and of course most Revenue-bringing) Setups, so in case you are enjoying your read and agree with all points so far, the Avant-garde point of view here is that you need Multiple CDNs catering to specific Geographies, or load balanced with each other into all of them.
The CNAME Records we’ve seen above will thus point to some load balanced Hostnames (instead of straight to your only CDN), and these in turn will point to a specific (CDN) Hostname depending – amongst the “simplest” possible logics – on the End Users’ geographic location. We bet your next question is: “How do these load balanced Hostnames then know and take decisions based on logics such as the End Users’ geographic location?” The answer is, my dear Reader, “More Advanced DNS (but not only DNS) Products are required to manage Multi-CDN Delivery Strategies”.
DYN’s Traffic Director is one such managed DNS Product which can efficiently distribute your Traffic from alternate Endpoints or Providers, leading to fewer dropped Requests and faster Response times. Traffic Director is made up of three Advanced DNS features: high Availability is achieved by rerouting traffic to other CDNs or Datacenters whenever an Outage is reported. Additionally, DYN’s Traffic Director enables Ratio Load Balancing (you can load balance assigning a “weight” or ratio to all involved outgoing Hostnames / CDNs, and Geolocation Load Balancing (as mentioned above, the possibility of routing german End Users to a given Hostname, and rest of the World elsewhere as an example).
This is important because a sudden surge in Traffic from a specific Geo-location can – and does often times – cause downtime. Load balancing becomes critical whenever sudden spikes in Traffic occur due to certain events. For example, in the recent World Cup we all witnessed downtime and / or congestion in many Networks, at some point, in some Geographies. Such situations can be handled and mitigated via more advanced DNS products such as DYN’s Traffic Director for instance.

Other approaches to Multi-CDN

We said “for instance” above, as in fact DNS and DYN aren’t the only way out of Single CDN / Origin Infrastructure Delivery. There are a few more contenders in the Multi-CDN Load Balancing space. Managing Multi-CDN through DNS and DYN is going for an advanced DNS Management Service. As discussed earlier, DYN’s Traffic Director ensures continuous, fast Delivery and high Availability of Networks by using Advanced DNS features. Another , even more sophisticated approach to Multi-CDN is via DNS based on HTTP Intelligence. We promote, amongst the rest of our Partners, Cedexis. Its “OpenMix” + “Radar” Products are an excellent example of this methodology. Cedexis has a sophisticated and intelligent Engine which analyzes Web Traffic Performance Key Metrics through its crowd-sourced Platform’s benchmarks and offers Application Load Balancing via more than a hundred Cloud Providers and five hundred Enterprises, possibly more. This approach leads to efficient Load Balancing and high Availability. Your beloved LinkedIn is one of its big customers from the USA, so take LinkedIn as an example of Cedexis’ Load Balanced Performance.

In Conclusion…

Businesses are facing extreme competition especially in the Online Domain. Even a small percentage of dropped or slow Traffic can be disastrous. A well-known E-Commerce Venture had to shut shop because its Website was unavailable for a few hours during the holiday season. This happened due to a sudden surge in traffic leading to an outage.
Customers are no longer limited to one geographical location, and this is both a challenge and an opportunity. Serving clients in China from the US and Europe can be effective only when we adopt a Single, if not even a Multi-CDN approach. This by itself is not enough though: we have to engage Advanced DNS Management Services to route Traffic efficiently and obviously the days of “in-house DNS” are over.
When adopting a Multi CDN Strategy, the choice is between managing it via DNS alone or based on some intelligent HTTP Engine on top. Both paths have their pros and cons and although the need for Advanced DNS Management is obvious and pays itself even easily, some Enterprises still hope to get through without incurring expenditure.
This mistake can cause incalculable harm to Businesses: a history of failed opportunities and disastrous consequences due to non-availability (or underperformance) of Networks can be easily looked up by a casual search on Google. Awareness and eternal vigilance is the cost we have to pay for our Online success, and Francesco Altomare Cloud Architect is here to assist.

This Post concludes our DNS Mini-Series although we’ll come back on DNS as a Topic in our future Posts, but now is time for you to interact with us!
Did you enjoy the Article? Is there anything we left unclear or that rose your interest?
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