A DNS checklist for an unreachable website

Work from the complete name to its addresses before moving further along the connection.

Use the name in the browser

First check whether you are visiting example.com or www.example.com. These names can have different settings. Remove the scheme and path from the browser address, query just the hostname, and look for spelling mistakes or an incorrect environment prefix.

Inspect addresses and aliases

Query A and AAAA. If an answer includes a CNAME, check its target as well. An address in a response only means that DNS supplied an answer; it does not prove that the address hosts the right website. An address change alone is not evidence of an attack.

Continue beyond DNS

If addresses match your provider’s instructions but the site is still unavailable, check certificates, ports, reverse proxies and application status next. This tool does not send website availability probes and therefore does not turn a successful DNS response into a “website healthy” claim.

This guide explains public DNS responses. Before changing production settings, check the documentation for your current domain and hosting providers.