220-1102 Question 563
Single answerSecure connections/sites–valid certificatesA technician is troubleshooting a browser warning on a company laptop when users visit https://portal.company.com. The warning states that the connection is not private and that the certificate is not valid for the website being viewed. The site loads normally for other internal users. The technician verifies that the web server certificate is current and was issued by a trusted public CA. Which of the following is the MOST likely cause of the warning on the affected laptop?
- A
The laptop's system date and time are incorrect
- B
The web server is using port 8080 instead of port 443
- C
The website requires a client certificate for authentication
- D
The browser cache contains an outdated copy of the website
Show answer and explanation
Correct answer: A
Explanation
The best answer is that the laptop's system date and time are incorrect. When a browser validates a website certificate, it checks that the certificate is within its valid date range, that the certificate chain leads to a trusted root CA, and that the certificate matches the hostname being accessed. In this scenario, the server certificate is confirmed to be current and trusted, and other users can access the same site successfully, which strongly suggests the issue is local to the affected device. An incorrect local clock is one of the most common causes of certificate warnings on a single system. This aligns with standard browser and PKI troubleshooting practices and vendor guidance from browser providers and operating system documentation, which note that inaccurate system time can trigger certificate validity errors.
- A. Correct.
Correct. If the laptop's date and time are significantly incorrect, the browser may determine that a certificate is not yet valid or has expired, even when the certificate is actually current. This is a common real-world cause of certificate warnings on a single device when the site works for other users. Valid certificate checks depend on accurate local system time.
- B. Incorrect.
Incorrect. HTTPS commonly uses port 443, but using a different port does not by itself cause a certificate name or validity warning. If the site were accessed over HTTPS on another port, the certificate could still be valid as long as the hostname matches and the certificate chain is trusted. Port selection is not the most likely explanation for a certificate-validity warning affecting only one laptop.
- C. Incorrect.
Incorrect. A site that requires a client certificate may block access or prompt the user to select a certificate, but that is different from a warning stating the site's certificate is not valid for the website being viewed. Client certificate issues relate to user/device authentication, not typically to server certificate validity for one endpoint.
- D. Incorrect.
Incorrect. Browser cache issues can cause display problems or old content to appear, but they do not usually produce a certificate validity warning about the secure connection. Certificate validation is performed during the TLS/SSL handshake and depends on the certificate, trust chain, hostname, and system time rather than cached page content.