When trying to access an internal website, an employee reports that a prompt displays, stating that the site is insecure. Which of the following certificate types is the site most likely using?

A self-signed certificate is generated and signed by the same entity that owns the website, rather than by a trusted third-party Certificate Authority (CA). Browsers do not inherently trust self-signed certificates because there's no independent verification of the site's identity. This lack of trust triggers security warnings, such as "site is insecure," when users attempt to access the website. While useful for internal testing or specific closed environments, they are inappropriate for public-facing websites due to these security alerts. Wildcard certificates cover multiple subdomains within a single domain but are still issued by a trusted CA, so they wouldn't cause "insecure" prompts. A "root of trust" refers to the initial trusted certificate in a PKI hierarchy, not a type of certificate used by an end-entity website. Third-party certificates are issued by trusted CAs and are designed to prevent such warnings.