1. Basic concepts -- 2. How NTP works -- 3. In the belly of the beast -- 4. Clock discipline algorithm -- 5. NTP system engineering and configuration -- 6. NTP performance in the Internet -- 7. Primary servers and reference clocks -- 8. Kernel timekeeping support -- 9. Cryptographic authentication -- 10. Identity schemes -- 11. Analysis of errors -- 12. Modeling and analysis of computer clocks -- 13. Metrology and chronometry of the NTP timescale -- 14. NTP reference implementation -- 15. Precision system clock architecture -- 16. NTP interleaved modes -- 17. Time transfer for space data links -- 18. Time transfer for deep-space missions -- 19. Technical history of NTP.