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DNS for Today’s Distributed Infrastructure | @CloudExpo #API #Cloud #DataCenter

Data centers have seen a lot of change in a short time

Data centers have seen a lot of change in a short time. It used to be possible for organizations to run their service from a single data center and house their Domain Name Service (DNS) servers within it. It wasn't an issue to have them in the same place, since if the data center went down, the DNS servers wouldn't be of any use.

Of course, things aren't so simple now. Organizations use multiple data centers, sometimes in multiple countries, not to mention cloud regions and highly distributed networks. Consequently, your DNS needs to be just as highly distributed as your content. After all, what good is a Disaster Recovery site if you have no way to direct your users to it?

Using multiple anycast groups and hundreds of servers spread out across the globe, top-notch DNS providers today offer highly resilient networks. However, the hard reality is that impairments, outages and massive Distributed Denial of Service (DDoS) attacks can and do happen. To truly bulletproof your distributed infrastructure against an issue where your users cannot resolve your domain, you might very well consider hosting your DNS records with two providers.

That would seem like a clear-cut solution at first, but consider the details. Prior to today's dedicated DNS solutions, you basically had three choices:

  • Run one DNS provider as primary and the second as the replicated slave
  • Run two DNS providers, both as primary, and (carefully!) make your record changes in each
  • Run two DNS providers, both as primary, and code your own middleware application that is capable of understanding a requested DNS change and pushing that change to each provider's unique API

Choosing the first scenario means losing the powerful geographic routing, traffic management features and RUM-based telemetry that some top-tier providers offer. The use of the zone transfer (XFR) technology condemns you to using only the most basic, plain-vanilla DNS records.

The second scenario leaves you wide open to human error. If you don't painstakingly and laboriously keep two different providers in perfect sync, you will end up with traffic routing problems that are shockingly difficult to troubleshoot.

Choosing the third scenario means dedicating substantial time and money to writing your own DNS management software suite, with in-depth integration with each of your DNS providers. You lose all the advantages of your providers' portals and dashboards and will have to roll your own interpretation layer to keep one provider's advanced features in approximate synchronization with the next provider's.

Again, times have changed, and there is a fourth choice today. Dedicated DNS solutions allow you to place real or virtual servers anywhere you want: in your office, in your data centers, inside your DMZs, behind your firewalls - literally anywhere that makes sense for your infrastructure. You can then install a DNS software stack on them and turn them into fully managed DNS delivery nodes that are dedicated to you. Through the same portal and API as you use right now to manage your DNS on a managed DNS anycasted world-wide platform, you can choose which domains you want to also serve from your dedicated DNS nodes.

What this option affords is a situation where you have all the resiliency of two DNS providers with the ease of management through a single portal and API. All your advanced traffic management and intelligent Filter Chain configurations work exactly the same too. If something were to happen to any part of the managed DNS infrastructure, your dedicated DNS nodes would be unaffected and would continue to happily serve DNS. Once they had reestablished contact with the "mothership," they would push their queued query statistics upstream and apply any pending record changes.

Dedicated DNS nodes are thus authoritative DNS servers, and they also support recursion, so you can point all your DNS clients (laptops, servers, EC2 instances, etc.) at them. This results in all your DNS needs being met and queries directed at your own domains and records being resolved in single-digit millisecond time. You can also leverage advanced Filter Chain capabilities to intelligently direct traffic within your own data centers and achieve greater performance, failover and resiliency between server or application tiers.

Ask anyone who's tried it: running two different DNS providers is difficult at best and a recipe for disaster at worst. Fortunately, modern dedicated DNS solutions offer the benefits of having two DNS providers by combining the features of managed DNS and dedicated DNS solutions for a more well-rounded and easier-to-manage environment.

More Stories By Nate Lindstrom

Nate Lindstrom is the VP of Solutions Engineering for NS1, an intelligent DNS and traffic management platform with a data-driven architecture purpose-built for the most demanding, mission-critical applications on the Internet. He has significant experience building, operating, and securing cloud environments, and has put his expertise to work at companies including Yahoo! and Salesforce. As an evangelist, public speaker and consultant he enjoys helping companies get the most bang for their buck with AWS and other cloud computing solutions.

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