A primary DNS server is the first point of contact for a browser, application or device that needs to translate a human-readable hostname into an IP address. The primary DNS server contains a DNS record that has the correct IP address for the hostname. If the primary DNS server is unavailable, the device contacts a secondary DNS server, containing a recent copy of the same DNS records.

How Does a Primary DNS Server Work?

When a computer or device needs to connect to another device on the Internet, it typically uses a human-readable domain name, like “www.example.com”. The browser or application needs to translate the domain name into a numeric Internet Protocol (IP) address like “192.100.100.1”. This translation is done by the Domain Name System (DNS).

The device first contacts the primary DNS server that hosts the controlling zone file. This file contains the authoritative DNS information for the domain or subdomain. “Authoritative” means it is the trusted source for information like the IP address of the domain, administrator contact information, and settings like Time to Live (how long this IP address should be saved in a local cache).

The primary DNS server server resolves the query by returning the IP address for the requested hostname. However, if the primary server is slow to respond, or is unavailable, the device is referred to one or more secondary DNS servers.

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