DNS outage: Meaning & Details

DNS outages can cause significant interruptions in business operations, so it’s essential to understand what they are and how to protect against them. A DNS outage, also known as a Domain Name System outage, is when an issue with the DNS server causes users to be unable to access the requested website or service. There are many different causes of a DNS outage, including malicious attacks, software and hardware errors, network congestion, and configuration errors. By having a DNS outage prevention plan and understanding the risks associated with DNS outages, businesses and individuals can ensure that they don’t experience any significant disruptions in their operations.

What is a DNS Outage? 

A DNS outage (DNS downtime) is a disruption in service on the Domain Name System (DNS), which is responsible for translating domain names into Internet Protocol (IP) addresses so that users can access online resources. An issue causes this outage with the DNS server, often due to an error, an attack, or a software or hardware failure. During a DNS downtime, users cannot access the requested website or service and often run into an error message. This can be a massive issue for businesses and individuals, as it prevents them from accessing crucial resources, services, and applications.

What Causes a DNS Outage?

There are many different potential causes of a Domain Name System downtime. One of the most common is an attack on the DNS provider by malicious actors, such as a DDoS attack, which floods the DNS server with too many requests and causes the system to become overloaded. Software or hardware errors can also cause a Domain Name System outage, as can an accidental modification to the DNS configurations resulting from human error. Additionally, a disruption in the power supply or hardware failure, such as a corrupted disk or memory, could also cause a DNS outage.

Another potential cause of a DNS outage is network congestion, when too much traffic is being sent or received at once, resulting in a backlog of data and an inability to process requests. In some cases, slow information propagation can also lead to a DNS outage, as the Domain Name System server may fail to recognize new changes to the system’s configuration. Finally, configuration errors due to incorrect setup or maintenance can cause a Domain Name System outage.

How To Detect a DNS Outage?

Detecting a DNS outage can be difficult, especially if you need to become more familiar with the inner workings of DNS servers and networks. But here are some of the most important ways to prevent your network against it:

  • Choose a reliable DNS service provider.
  • Back up (Secondary DNS) and test the DNS server system.
  • Implement authentication and data encryption.
  • Apply software updates to DNS servers and other methods.
  • Deploy Monitoring service tools and alerting systems.
  • Invest in security tools such as DDoS protection services.
  • Isolate internal networks from external threats.
  • Ensure secure configurations (DNSSEC) and limit access to the DNS server.
  • Regularly check for vulnerabilities in the system.

What are the most memorable DNS outages in history?

  1. The notorious “Dyn DNS” outage in October 2016 was caused by a massive DDoS attack, disrupting the internet for millions of people in North America and worldwide. 
  2. According to research from VeriSign, the average cost of a network incident caused by a DNS outage can be as high as $2.72 million. 
  3. Additive costs resulting from a Domain Name System downtime can include a 7-10% dip in customer satisfaction, lost time and resources due to troubleshooting, and decreased productivity or missed sales. 
  4. The United Nations estimates that each hour of lost internet connectivity can cost businesses up to $120,000 in lost revenue. 
  5. In June 2020, a significant outage occurred within the Amazon Domain Name System service resulting in downtime for millions of Amazon Web Services customers. 
  6. The peak DNS queries per second rate (DNS QPS) reached its highest levels when the pandemic hit, with over 1450 DNS QPS compared to the normal rate of 700-1000. 
  7. In October 2020, a significant downtime in Google’s DNS service caused service interruptions for services such as YouTube, Gmail, and Google Docs for several hours. 
  8. A recent report from Renesys estimates that 40% of global networks are vulnerable to DNS outages due to a lack of proactive prevention measures.


DNS outages can significantly impact businesses, so it’s essential to understand the risks and have strategies to prevent them. Ensure that you’re using a reliable DNS service provider, regularly update DNS software, and apply authentication and data encryption. Additionally, monitor and alert for any potential problems, use redundancy with other DNS providers to minimize the impact of an downtime, secure configurations, limit access to the DNS server, or isolate your internal networks from external threats. If a DNS outage does occur, you’ll be able to identify the source quickly and handle it properly. Having suitable measures in place can help your business to remain productive and secure.

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