DNS
DNS (Domain Name System) is the global infrastructure that translates human-readable domain names into IP addresses. It is what allows browsers to find example.com when you type it. DNS operates as a hierarchical, distributed database with root servers at the top, TLD servers underneath, and authoritative nameservers for individual domains at the bottom.
Also known as: Domain Name System
In depth
DNS resolution starts at the root — a small set of servers (the "root nameservers") that know which servers are authoritative for each top-level domain. The root tells you which servers handle .com; .com servers tell you which nameservers handle example.com; example.com's nameservers give you the actual IP address.
For domain monitoring, DNS is one of three signals (along with EPP status and WHOIS/RDAP data). When a domain enters redemptionPeriod, its DNS is suspended — the website stops resolving. Domain monitoring tools can use DNS NXDOMAIN responses as a fast signal that something has changed.
DNS itself does not tell you anything about ownership or expiry. To know whether a domain is registered you need to query the registry via WHOIS or RDAP. To know whether it resolves to a working website you query DNS. Both signals together give a complete picture.
Examples
- Querying example.com from a typical resolver: dig example.com → returns 93.184.216.34.
- A domain in redemptionPeriod returns NXDOMAIN — the DNS lookup fails because the domain has been removed from DNS.
- A domain in clientHold also returns NXDOMAIN even though the registration still exists.
Frequently asked questions
What is DNS used for?
Translating domain names into IP addresses so your browser knows which server to connect to. Without DNS you would have to remember IP addresses for every site.
How does DNS relate to WHOIS?
They are independent. WHOIS tells you about the registration (who owns it, when it expires). DNS tells you where the domain points (which server). A domain can have valid registration but broken DNS, or working DNS but expired registration.
What is NXDOMAIN?
A DNS response indicating the domain does not exist (or has been removed from DNS). This happens for unregistered domains, domains in redemptionPeriod, and domains under clientHold or serverHold.
How do I change a domain's DNS?
Update the nameservers at your registrar. The change typically propagates worldwide within 24-48 hours.
Is DNS encrypted?
Traditional DNS is not. Modern variants (DNS over HTTPS, DNS over TLS) encrypt queries between client and resolver but the underlying authoritative DNS protocol remains unencrypted.
Related terms
References
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