The URL or its content (such as files or images) was either deleted or moved (without adjusting any internal links accordingly)
The URL was written incorrectly (during the creation process or a redesign), linked incorrectly, or typed into the browser incorrectly
The server responsible for the website is not running or the connection is broken
The requested domain name can’t be converted to an IP by the domain name system (DNS)
The entered domain name doesn’t exist (anymore)