Why You Need a Distributed DNS Implementation – The New Stack

Seraline Barthelmy

Sheraline is Head of Product, Marketing and Customer Success at Cox Edge, a Cox Communications cloud startup. At Cox Edge, she focuses on developing the tools and systems that customers and developers rely on to build the next generation of cutting-edge applications.

Long-distance relationships are difficult to maintain. Distance increases the risk of a communication breakdown.

Networking, like life, has the same problem.

Source and destination IP addresses separated by country or continent result in latencies of hundreds of milliseconds, rendering real-time applications unnecessary.

For online games, augmented and virtual reality, critical machinery monitoring sensors, or emergency hospital monitoring equipment, latencies greater than 7-10 milliseconds can mean motion sickness, risk of machinery resulting in fires or explosions and delayed treatment that could endanger the life of a patient.

While edge computing can solve the problem of distance to a large extent by bringing compute, storage, and analytics closer to end users and their devices, things can still go down due to a resolution. delayed domain name system (DNS).

Recursive DNS resolvers that send end-user queries to authoritative nameservers halfway around the world, or DNS resolutions that match servers in another country, can negatively impact latency and real-time application response.

IP Anycast is designed to solve this problem.

Efficient routing

Anycast is a network addressing and routing method that simultaneously advertises the same IP address from multiple servers on a network. Border Gateway Protocol calculates the shortest topological path between source and destination, and routes user requests to the closest server.

If the chosen server goes down, Anycast chooses the next available server (after recalculating the shortest path) and redirects the user’s request without changing the destination IP.

DNS and Anycast are a perfect combination. DNS queries have small packet sizes which make communication through User Datagram Protocol more efficient than Transmission Control Protocol (TCP). TCP, being a reliable protocol, needs a three-way handshake and performs retries and other functions that consume bandwidth.

User Datagram Protocol (UDP) sends the packet and forgets it. There are no retries or attempts to establish trusted connections. A DNS query is small enough to fit in a single UDP packet. Anycast for DNS routes client queries to the nearest DNS server. If that server goes down, Anycast automatically redirects the DNS query to the next available (and closest) IP address without client intervention.

Since the communication is via UDP, it makes no difference which DNS server responds. Unlike TCP, there is no need to reestablish connections, which saves time and bandwidth.

Content Delivery Network (CDN) providers use Anycast to route users to the closest available edge server, automatically redirecting them to the closest available server if the original chosen server goes down.

DDoS Mitigation

Another significant advantage of Anycast is Distributed Denial of Service (DDoS) mitigation. After DDoS mitigation techniques filter out some of the attack traffic, Anycast distributes the remaining traffic across the data centers, preventing one location from being overwhelmed with requests. As the network grows in size and capacity, standard DNS traffic consumes a fraction of the name server’s capacity, making it difficult for attackers to reach a high volume of distributed DDoS traffic.

While Anycast is designed to protect servers against the most sophisticated DDoS attacks, network engineers must ensure that DNS servers continue to respond to end-user requests even if multiple nodes fail.

With a global server footprint, many leading CDN providers can commit to 100% uptime by limiting the number of Anycast IP addresses they advertise. Edge data centers that go down could take part of the Internet with them if every DNS query is resolved to that data center – which would be the case if that point-of-presence (POP) router advertised every Anycast IP address .

To prevent this from happening, Edge POPs only advertise a few Anycast cloud IP addresses, which is designed to ensure that requests are routed to healthy data centers.

Enjoy the benefits of 5G

The world’s largest CDN provider combines Anycast with several implementation options that improve the performance and reliability of its DNS solutions. Zone Apex Mapping (ZAM) is one of them.

ZAM resolves top-level hostnames directly to optimal Edge Server IP addresses, eliminating the latency induced by CNAME chain tracking and reducing DNS lookup times for hostnames on their platform.

With the scalability, reliability, and flexible implementation options that Anycast DNS offers, it looks set to play an important role in the adoption of new technologies, like 5G.

With over 580 million subscribers in 2021, 5G is becoming perhaps the fastest mobile platform ever adopted. Applications such as IoT, edge computing, self-driving cars, healthcare, and AI-based use cases will benefit from 5G’s ultra-low latency and processing speed.

That said, network operators have their work cut out for them. Deploying 5G involves much more than upgrading Radio Access Network (RAN) infrastructure from the current LTE standard. Operators will need to review their mobile network architecture, starting with DNS, if their subscribers want to reap the benefits of 5G.

The current DNS architecture with servers deployed in a few regional POPs does not achieve the latency required for applications based on real-time interaction. 5G-enabled apps that require ultra-low latency (

Prior to 5G, RAN provided latencies of around 50 milliseconds, which masked DNS latency. But with 5G, latency drops to less than 5 milliseconds, and a slow DNS lookup would affect critical communications that might require latencies of less than 5 milliseconds.

Get closer to the edge

Edge Computing moves resources to the edge of the network, closer to users and devices that generate data. This reduces latency and the amount of traffic routed over mobile networks to a central cloud.

Anycast DNS implementations enable large-scale deployments of DNS servers in edge data centers, allowing applications to have the short DNS lookup times they need. Cox Edge, a leading development platform, offers Anycast DNS solutions that provide end users with exceptionally low query latency.

Users get nearly instant DNS record changes, ideal for use cases like migrations and failover. The Edge Anycast platform has essential features such as fast resolution that serves DNS data from the edge of the cloud. Intelligent routing funnels DNS traffic to an optimal DNS server, and near real-time propagation pushes all DNS updates worldwide in seconds.

With edge computing becoming the new norm, distributed DNS implementations such as Anycast DNS are set to become the foundation for the next generation of real-time applications.

The New Stack is a wholly owned subsidiary of Insight Partners, an investor in the following companies mentioned in this article: Real.

The selected image via Pixabay.

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