What is a DNS Error? Causes & Fixes
Definition
A DNS error occurs when a client cannot resolve a domain name to an IP address using the Domain Name System. Because DNS resolution happens before any HTTP request, a DNS failure means the connection never reaches your web server — there is no HTTP status code to inspect.
Common DNS errors
- NXDOMAIN — the domain does not exist (typo or expired registration).
- SERVFAIL — the authoritative DNS server is unreachable or returned an invalid response.
- Timeout — the resolver did not get a response in time, often a network or firewall issue.
- NS misconfiguration — nameservers point to the wrong DNS provider after a migration.
SEO and monitoring impact
- Repeated DNS errors during Googlebot crawls can cause de-indexing.
- DNS errors are invisible to most uptime monitors that test only HTTP — set up explicit DNS checks.
- When auditing inbound or outbound links, a DNS failure produces a different error class than a 404 or 500. Scan your site to detect both.
DNS errors are infrastructure problems, not application bugs. Monitor your nameservers, keep registrar contact details current, and never let a domain expire silently.
Related terms
Dead Link
A hyperlink that points to a page or resource that no longer exists.
404 Error
What happens when a page can't be found — and how it affects SEO.
301 Redirect
The permanent redirect that preserves link equity and guides users.
Crawl Budget
How search engines allocate resources to crawl your site — and why broken links waste it.
Broken Link
A hyperlink that no longer leads to its intended destination.
Redirect Chain
Multiple redirects in sequence that slow down pages and dilute SEO value.