N10-009 Question 235
Single answerTime protocols: NTP, Precision Time Protocol (PTP), Network Time Security (NTS)A financial trading company is upgrading the timing design for two different environments. The first environment is a data center segment that supports latency-sensitive market data systems and requires sub-microsecond clock synchronization between servers. The second environment is a group of remote branch routers that synchronize time across the public Internet, and the security team is concerned about spoofed or tampered time responses. Which solution best meets both requirements?
- A
Deploy PTP in the data center segment and use NTP with NTS for the branch routers
- B
Deploy NTP with NTS in both environments because it provides the highest precision and authenticated time
- C
Deploy PTP in both environments because it is designed for WAN use and includes built-in cryptographic authentication
- D
Deploy basic NTP in the data center segment and unauthenticated PTP for the branch routers
Show answer and explanation
Correct answer: A
Explanation
The best answer is to use PTP where very high precision is required on a controlled local network and to use NTP with NTS where time must be distributed securely over the public Internet. PTP, defined by IEEE 1588, is designed for precise clock synchronization and is widely used when applications need very low jitter and very small offset between systems. In practice, it often relies on hardware timestamping and PTP-aware switches such as boundary clocks or transparent clocks to achieve its best accuracy. NTP remains the standard general-purpose time synchronization protocol for IP networks, especially across WANs and the Internet. NTS, standardized by the IETF for NTP security, adds mechanisms for server authentication and protection against certain on-path tampering and spoofing attacks. This aligns with best-practice guidance: choose PTP for precision-focused local environments and NTP with NTS for secure, scalable time synchronization over less trusted networks.
- A. Correct.
Correct. Precision Time Protocol (PTP, IEEE 1588) is the appropriate choice for the data center segment when very high precision, such as sub-microsecond synchronization, is required. PTP is commonly used in environments like finance, telecom, and industrial networks, especially when supported by boundary clocks or transparent clocks in the switching infrastructure. For branch routers synchronizing over the public Internet, Network Time Protocol (NTP) is the practical protocol, and Network Time Security (NTS) adds authentication and integrity protection to help defend against spoofed or modified NTP traffic.
- B. Incorrect.
Incorrect. NTP with NTS improves security for NTP by authenticating the time source and protecting the exchange, but it does not generally provide the same level of precision as PTP for sub-microsecond synchronization in a local high-performance network. A candidate might choose this option because NTS sounds like a comprehensive enhancement, but it addresses security for NTP rather than turning NTP into a high-precision replacement for PTP.
- C. Incorrect.
Incorrect. PTP is primarily intended for high-precision timing on local networks and usually depends on network devices that understand or support PTP for best results. It is not generally the preferred choice for synchronization of remote branch routers across the public Internet. Also, standard PTP does not simply solve the Internet-facing authentication concern described here in the same way NTP with NTS does. This option reflects the misconception that the most precise protocol is automatically the best fit for every topology.
- D. Incorrect.
Incorrect. Basic NTP is typically not sufficient for sub-microsecond synchronization in a latency-sensitive data center trading environment, and unauthenticated PTP for Internet-connected branch use does not address the stated security concern about spoofed or altered time responses. This option reverses the appropriate use cases for the protocols and ignores the need for secure time distribution over untrusted networks.