Why You Shouldn’t Be Hosting Public DNS

As a former Unix engineer who managed my share of critical network services, one of the first things I do when evaluating an organization is to validate the health of infrastructure components such as NTP, RADIUS, and DNS. I’m often shocked by what I find. Although most people barely understand how these services work, when they break, it can create some troublesome technical issues or even a full meltdown. This is especially true of DNS.

Most problems with DNS implementations are caused by the fact that so few people actually understand how the protocol is supposed to work, including vendors.The kindest thing one can say about DNS is that it’s esoteric. In my IT salad days, I implemented and was responsible for managing the BIND 9.x infrastructure at an academic institution. I helped write and enforce the DNS request policy, cleaned up and policed the namespace, built and hardened the servers, compiled the BIND binaries and essentially guarded the architecture for over a decade. I ended up in this role because no one else wanted it. I took a complete mess of a BIND 4.x deployment and proceeded to untangle a ball of string the size New Zealand. The experience was an open source rite of passage, helping to make me the engineer and architect I am today.  I also admit to being a BIND fangirl, mostly because it’s the core software of most load-balancers and IPAM systems.

This history makes what I’m about to recommend even more shocking. Outside of service providers, I no longer believe that organizations should run their own public DNS servers. Most enterprises get along fine using Active Directory for internal authentication and name resolution, using a DNS provider such as Neustar, Amazon or Akamai to resolve external services. They don’t need to take on the risk associated with managing external authoritative DNS servers or even load-balancing most public services.

The hard truth is that external DNS is best left to the experts who have time for the care and feeding of it. One missed security patch, a mistyped entry, a system compromise; any of these could have a significant impact to your business. And unless you’re an IT organization, wouldn’t it be better to have someone else deal with that headache? Besides, as organizations continue to move their services to the cloud, why would you have the name resolution of those resources tied to some legacy, on-premise server? But most importantly, as DDoS attacks become more prevalent, UDP-based services are an easy target, especially DNS. Personally, I’d rather have a service provider deal with the agony of DDoS mitigation. They’re better prepared with the right (expensive) tools and plenty of bandwidth.

I write this with great sadness and it even feels like I’m relinquishing some of my nerd status. But never fear, I still have a crush on Paul Vixie and will always choose dig over nslookup.

 

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One thought on “Why You Shouldn’t Be Hosting Public DNS

  1. […] Chubirka from Post Modern Security  spent ten years as a sysadmin with a primary focus on managing a BIND DNS for a very large […]

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