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How to Compare Hosted DNS Providers (with Data!)

Introduction

Photo 25499

My colleagues & I run a popular website and are constantly concerned with scaling and performance. Until last week, we had been running our own DNS servers (BIND) on Amazon EC2 instances.

We use Pingdom to monitor many functions of our servers, including DNS. What we saw was a resonable average resolution time of about 130ms, but frequent outliers higher than 500ms! The thought of a half-second penalty to the load time for first time visitors is not appealing. So we started to dig into the problem.

Background

DNS, or Domain Name System, is one of the core pieces of infrastructure on the Internet. Its essentially a distributed database, that allows us to convert from human-readable hostnames to IP addresses quickly. For instance, if you type 'sat.learnhub.com' into your web browser, it will contact your DNS server which will return "75.101.155.247". Then your web browser will make an http request to that IP address and actually retrieve the webpage. Its all transparent to you, the end user, apart from the time it takes.

If the DNS server your browser contacted does not have the IP address cached, then it will attempt to locate and contact an "authoritative name server". Most sites have 2 or more.

Site operators can either run these authoritative name servers themselves, or outsource it to another company. Often these services are provided for free by domain name registrars. The most popular software to run your own DNS servers is BIND.

Hosted DNS Providers

Popular websites get hundreds of DNS queries per second (QPS), often from all over the world. To maintain consistently fast DNS resolution times, say < 100ms, the necessary solution is to have a distributed network of DNS servers. There are many companies that provide hosted DNS services. After some researched, we narrowed our search to these 4.

Service Notes
DNSMadeEasy From Tiggee. Very low cost ($30/year). The others are significantly more expensive.
Dynect From Dyn Inc. A younger company better known for consumer (DynDNS) not enterprise DNS solutions.
Netriplex Very friendly salesperson and the longest list of global DNS servers.
UltraDNS From NeuStar, which is a publicly traded company. They seem to be the largest and most established in this market.

List with more hosted DNS services »

I exchanged phone calls and emails with representatives from all these companies to understand their pricing etc. All but one go by a fixed number of queries (lookups) per month. Dynect goes by a more complicated 95th percentile QPS (Queries Per Second). The benefit of Dynect's model is that it is forgiving of bursts of traffic.

Pingdom Website Monitoring

Pingdom Logo
We signed up for Pingdom months ago to monitor our site and services and to send us SMS messages if the site goes down. It turns out, Pingdom is useful for measuring DNS and HTTP response times too. Pingdom uses data centers in 14 (or so) locations around the world, though mostly just in North America and Europe. I wish they were in India as well.

Results

Pingdom works by setting up "Checks". They can be of different kinds… so far I've only used HTTP and now DNS. Normally you would set up Checks for your own sites and services, but there is nothing stopping you from setting them up for others. So that's just what I did.

I set up 4 new checks, one for each of the hosted DNS providers I'd shortlisted. I set the checks to the shortest interval, 1 minute. I picked sample sites that I knew used each one, and picked the first of each providers DNS servers.

The first observation I had was that DNSMadeEasy was clearly not as good as our current set up. It was averaging over 150ms (compared to our current 130ms) and had many outliers even higher than what we were already experiencing. After a day of watching that I removed the check and gave up on them. I no longer have the data, but I'm sure you'd find the same thing if you tested it again yourself with Pingdom.

Here's the data for the remaining three:

DNS Server Test site Average Response Time Standard Deviation
ns1.p19.dynect.net Shopify.com 42ms 60
ns1.netriplex.com LuiLui.com 78ms 109
udns1.ultradns.net Digg.com 80ms 448

It looked like UltraDNS, in addition to having the highest average, also had the highest standard deviation by a considerable margin. This was due to many extremely long samples. Both Dynect and Netriplex were much more consistent.

Conclusion

In my 3-day test, Dynect demolished the others. It was more consistent and had a much lower average response time.

I also happen to like Dynect's pricing model and user interface better as well, so the decision to go with them was pretty easy.

We did the cut over last week, and its all gone very smoothly. Here is our response time graph since the start of the year:

Photo 25498

You can see that our average response time dropped significantly this last week. We are averaging around 45ms now. And we no longer expect spots of poor performance. (You can see 2 points in the graph where the average response time is around 350ms.)

The point of this lesson however is not to convince you to use Dynect or any other service. Instead I'm trying to show how to creatively use Pingdom's website monitoring service to help you make more empirical decisions about hosted DNS providers.


If you are interested in DNS, join the DNS Community on LearnHub for more.

  1. Papabearshoe saidThu, 09 Apr 2009 14:57:07 -0000 ( Link )

    cool….

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  2. CloudyDaze saidThu, 09 Apr 2009 18:08:13 -0000 ( Link )

    Great stuff! I wonder if there outcome is the same for just US lookups? My audience is just stateside so I’d hate to move DNS services if the outliers in your study were all international.

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  3. Andrew Brown saidThu, 09 Apr 2009 19:46:50 -0000 ( Link )

    Thanks for the awesome walkthrough

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  4. oLahav saidFri, 10 Apr 2009 14:16:08 -0000 ( Link )

    Wow, I didn’t even know what a DNS server is, but I still managed to get the ideas behind the lesson. Good one!

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  5. teroz saidTue, 14 Apr 2009 06:05:33 -0000 ( Link )

    i thought OpenDNS should have been included in this review

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  6. rduck saidSun, 26 Apr 2009 07:18:47 -0000 ( Link )

    A very Informative review based on actual experience. Thank You for sharing.

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  7. Simonjonzie saidThu, 07 May 2009 17:22:58 -0000 ( Link )

    if you’re looking to compare DNS providers you should really check out www.dnsreviews.com. they have descriptions of the most well established DNS hosting companies and user reviews as well. Seems to be a pretty new site, but i posted a review there and the information is very useful.

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  8. mvardany saidWed, 13 May 2009 19:18:13 -0000 ( Link )

    you can check also http://www.monitis.com, they provide quite advanced DNS check which not only measures response time but also resolution of particular domain in the specified DNS server, cause sometime there are problems with resolution itself and not response time. also if you’re using EC2 instances they provide EC2 instance specific monitoring as well as internal monitoring, so I suggest to give it a try

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  9. kyork20 saidThu, 18 Jun 2009 18:21:28 -0000 ( Link )

    Break Free: http://204.13.248.102
    Full disclosure: brought to you from Dyn Inc.

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  10. Dest saidThu, 14 Jan 2010 19:19:10 -0000 ( Link )

    Hey, thanks a lot! Now I know how to chose the best DNS provider ;)

    http://www.czech-netz.com

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  11. matthewclegg saidSat, 30 Jan 2010 18:31:20 -0000 ( Link )

    Thank you very much for taking the time to put together this very helpful research.

    It is important to keep in mind though that the results of a study like this can be very dependent not only on the quality of service of the DNS provider but also of the location of pingdom in relation to them. To take an extreme example, if a DNS provider had its servers colocated in the same data center as those of pingdom, then pingdom’s measurements of the their quality of service would be biased in their favor. To get the most accurate results, you would need to make DNS queries from a collection of sites that are representative of your customer base.

    Also, the standard deviation measurements may be a bit misleading. A single very slow query (e.g., dropped packet) can result in a greatly increased standard deviation.

    I have no relationship with any of the sites or parties mentioned on this page. I just happened to study some of these issues when I was doing my computer science Ph.D. (which of course entitles me to bloviate ad nauseam with an annoying pretense of useful knowledge).

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  12. msantini saidThu, 11 Mar 2010 18:04:16 -0000 ( Link )

    I had just signed up with DNS Made Easy recently and came across this article as I was shopping around. I was surprised at the information here which must be very outdated at this point. Typical response times from their servers have been between 30 and 40ms all along the board and that is for anycasted dns that is 1/100th of the price you can find it anywhere else. After the testing the service myself…they definitely got my business.

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  13. TSamuels saidFri, 12 Mar 2010 12:42:55 -0000 ( Link )

    DNS Made Easy has really increased their performance since this review. You might want to redo your stats so users can get a better chance of using a more affordable enterprise solution.

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  14. ddurrer saidWed, 07 Apr 2010 17:34:17 -0000 ( Link )

    Also could have to do with certain pingdom monitors going offline or online. Or dynect adjusting routes to the pingdom monitor sensors.

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  15. gemal saidTue, 20 Apr 2010 19:00:58 -0000 ( Link )

    Please add gratisdns.dk

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  16. gemal saidTue, 20 Apr 2010 19:05:11 -0000 ( Link )

    Please add gratisdns.dk

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  28. ccrosby saidWed, 11 Aug 2010 23:27:30 -0000 ( Link )

    Interesting article. I’d be curious to read an update to this as well: hear how its going, etc.

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  29. ccrosby saidWed, 11 Aug 2010 23:31:08 -0000 ( Link )

    Interesting. How about an update on how well things have been going since then? I’m curious too how DNSMadeEasy is fairing these days as well.

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  30. ccrosby saidWed, 11 Aug 2010 23:31:25 -0000 ( Link )

    Interesting. How about an update on how well things have been going since then? I’m curious too how DNSMadeEasy is fairing these days as well.

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  31. shave saidThu, 04 Nov 2010 20:26:53 -0000 ( Link )

    you can compare your DNS records at-
    http://sharontools.com

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  32. Simonjonzie saidThu, 30 May 2013 00:53:42 -0000 ( Link )

    might wanna check out www.dnsreviews.com

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  33. Lilybelle saidWed, 14 Aug 2013 19:16:10 -0000 ( Link )

    The Domain Name System (DNS) represents naming system for computers, services, or any resource connected to the Internet.
    http://www.limyservers.com/

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