What is DNS redundancy?
DNS redundancy refers to the practice of having multiple Domain Name System (DNS) servers in place to ensure continued functionality in the event of a single server failure or a distributed denial of service (DDoS) attack. Distributing DNS queries across multiple servers minimizes the risk of a single point of failure and improves the overall reliability and availability of the system.
See also: DNS failover, Anycast DNS, DNS query, DNS filtering, DNS cache, DNS
How does DNS redundancy work?
DNS redundancy works by distributing DNS records across several servers so that a failure on one does not stop name resolution. In most setups:
- Primary and secondary servers store the same DNS information, allowing the secondary server to respond if the primary goes offline.
- Traffic distribution ensures DNS queries are handled by whichever server is available or closest.
- Failover mechanisms automatically direct requests to backup servers if the main DNS server is slow or unreachable.
- Anycast DNS can route users to the nearest functioning DNS server to improve speed and resilience.
DNS redundancy examples
- Primary and secondary DNS servers: A primary DNS server holds the original DNS records, while the secondary DNS server maintains a copy of these records. If the primary server fails, the secondary server can continue resolving domain names.
- Anycast DNS: Anycast is a networking technique that allows multiple servers with the same IP address to be distributed globally. When a DNS query is made, it is routed to the nearest server, improving response times and providing redundancy.
What are the benefits of DNS redundancy?
- Improved reliability: By distributing DNS queries across multiple servers, the likelihood of a single point of failure is reduced.
- Enhanced performance: With Anycast DNS, users' queries are directed to the nearest server, reducing latency and improving response times.
- Increased resilience against cyberattacks: DNS redundancy can help mitigate the impact of DDoS attacks by distributing the attack traffic across multiple servers.
Why is DNS redundancy important?
DNS is a critical service — if it fails, users cannot reach your website or online systems, even if the servers themselves are working. DNS redundancy protects against:
- Single points of failure, ensuring business continuity.
- Hardware or network outages at a DNS provider.
- Service interruptions caused by maintenance or configuration errors.
- DNS-based attacks, where attackers try to overwhelm one DNS server.
- Performance bottlenecks, since distributing DNS traffic avoids overload.
By having multiple DNS servers available, organizations maintain a stable and reliable online presence.
DNS redundancy tips
- Utilize both primary and secondary DNS servers to maintain an updated copy of DNS records.
- Consider implementing Anycast DNS to improve performance and resiliency.
- Monitor your DNS infrastructure regularly to detect potential issues and respond to them swiftly.
