220-1101 Question 98
Single answerNetwork Time Protocol (NTP)A technician is troubleshooting several Windows workstations that cannot log in to cloud-based applications after a recent firewall change. Users report certificate warnings and authentication failures. The technician notices the PCs all show times that are several minutes different from the company domain controller and internet time sources. Which action is the BEST way to resolve the issue across the affected PCs?
- A
Configure the affected PCs to synchronize their clocks with a valid NTP time source
- B
Increase the display refresh rate on the affected PCs so authentication prompts update correctly
- C
Assign static IP addresses to the affected PCs to prevent time drift
- D
Disable certificate validation in the affected applications until users can log in again
Show answer and explanation
Correct answer: A
Explanation
The best answer is to configure the affected PCs to synchronize with a valid NTP source. Accurate time is critical for modern authentication and encryption workflows. If a workstation clock is too far out of sync, cloud services, TLS/SSL certificate validation, and domain-based authentication may fail. In Microsoft environments, clients commonly sync time from the domain hierarchy, while standalone systems may use approved internet NTP servers. NTP traditionally uses UDP port 123, so firewall changes can interfere with synchronization if that traffic is blocked. This aligns with standard best practices from operating system and network administration documentation: fix the underlying time source and verify that required NTP traffic is allowed rather than weakening security controls or changing unrelated settings.
- A. Correct.
Correct. NTP is used to synchronize system clocks with a reliable time source. Significant time drift can cause authentication failures, Kerberos issues, and certificate validation errors because many security systems depend on accurate timestamps. Pointing the systems to a valid internal or external NTP source is the appropriate fix.
- B. Incorrect.
Incorrect. Display refresh rate affects how often the monitor redraws the image and has nothing to do with system time, certificate trust, or authentication. This distractor reflects confusion between hardware display settings and operating system clock synchronization.
- C. Incorrect.
Incorrect. IP addressing does not control clock accuracy. A workstation can have either a static or dynamic IP address and still maintain correct time if it is configured to use an NTP source. This option reflects a common misconception that all network-related issues are tied to IP configuration.
- D. Incorrect.
Incorrect. Disabling certificate validation is not a proper fix and creates a security risk. Certificate checks rely on accurate system time to verify validity periods, but bypassing those checks weakens security instead of solving the root cause. Best practice is to correct time synchronization rather than disable protections.