What is a DNS Server

What is a DNS Server

A Domain Name System, or DNS, server is a device that responds to a DNS query, working to deliver the correct IP address to the client. DNS servers make a website’s IP address available to a web browser through the DNS client embedded in a computer or mobile operating system.

DNS Servers may be primary DNS servers or secondary DNS servers. The primary DNS server will contain all of the relevant zone and record information used within a network. The secondary DNS server will contain read-only copies of zone information and is used mostly for resiliency and redundancy, but may also be used for load balancing.

How Do DNS Servers Resolve DNS Queries or Lookups
Types of DNS queries
What is DNS caching?

DNS server failure

There’s a multitude of reasons why a DNS server may fail. From hardware malfunctioning to power outages and cyber-attacks, a server failure can catch you off guard. Earlier on, outages could affect an organization severely. Lately, there are a lot more contingencies within DNS. TLD nameservers and root DNS servers often have multiple instances. The same goes for authoritative nameservers. Internet Service Providers (ISPs) also offer backup recursive resolvers to their subscribers. During a widespread DNS server outage, some clients’ queries may be delayed due to the large amount of requests that backup servers would have to handle. However, it would take a very massive attack to have the kind of outage that leaves a considerable portion of web information unavailable.

This has actually happened before in the form of a Distributed Denial of Service (DDoS) attack on a DNS provider called Dyn in 2016, using Mirai malware. It is therefore extremely crucial to opt for a DNS provider that not only has robust secure DNS features to protect against such attacks, but also has backup servers to reduce any resultant downtime from an effective cyber attack or some other issue.

What does this error mean?
What do when it is not responding?
How to fix it: