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?

Wildcard certificates are used to secure multiple subdomains of a domain under a single certificate issued by a trusted CA. Since they are validated by a CA, they do not typically trigger security warnings. Therefore, they would not be the cause of the insecure site prompt reported by the employee.

A root of trust refers to a set of security foundations, typically established through trusted CAs, to validate the authenticity of digital certificates. This concept does not directly relate to individual certificates being used on a website, nor does it imply the presence of any security warnings, making it an incorrect choice.

Third-party certificates are issued by recognized certificate authorities that validate the identity of the website owner. These certificates are designed to prevent insecure prompts. Since they are trusted by browsers, they would not typically result in the described warning, ruling them out as the certificate type in question.