What is a DNS Server

Domain name system server, DNS Server, points network resources (online, hardware, etc.) and forwards requests from clients to their respective locations.

ADomain NameSystem, orDNS, 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.

When a client makes a DNS query or DNS lookup with no caching, there are at least four servers involved in delivering the required IP address to the client. This happens via the following process:

DNS Resolver Server: The client queries the DNS Resolver specified in its network configuration settings.

Root Name Server Query: The DNS resolver receives the query from the client and starts by querying the root nameserver. The root nameserver responds with an address of a Top Level Domain (TLD) DNS server (like .com or .net) that has information for its domains.

Top Level Domain Server: The DNS resolver then queries the TLD server recommended by the root nameserver. The TLD server provides an IP address of the relevant domain’s authoritative name server.

Authoritative Name Server: The recursor finally sends a query to the prescribed authoritative name server, which replies with the origin server’s IP address.

This is the address that the DNS resolver sends back to the client. The client can then use this IP address to communicate directly with the origin server and receive website information that the browser can comprehend and display. This will happen through an HTTP request by the browser.

Having a DNS cache, or DNS caching, refers to the practice of a DNS server (particularly a recursive resolver) storing an IP address from a specific query for a limited amount of time. Any other request from clients where the corresponding address is in the cache can be handled swiftly without involving the other servers.

The duration over which the IP address can be stored in the cache is called the Time-to-Live (TTL), and is determined by the records for each site.

TTLs often range from 24 to 48 hours and are needed since web servers periodically change their IP address, meaning that at one point the saved address may no longer match the query. DNS data can also be stored in various locations.

Caching can happen at browser level and also at the operating system level (this one comes in handy for other applications that require an internet connection for a given task).

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What is a DNS Server

What is a DNS Server

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