# NTP-related RFCs
This is a curated list of RFCs that are about **Network Time Protocol (NTP)** and closely related companion specs (SNTP, NTS, DHCP options, and NTP management).
## Core NTP protocol specifications
- **RFC 958** — Network Time Protocol (NTP) (1985)
- **RFC 1059** — Network Time Protocol (version 1) specification and implementation (1988)
- **RFC 1119** — Network Time Protocol (version 2) specification and implementation (1989)
- **RFC 1305** — Network Time Protocol (Version 3) Specification, Implementation and Analysis (1992)
- **RFC 5905** — Network Time Protocol Version 4: Protocol and Algorithms Specification (2010)
## SNTP (Simple NTP) specifications
- **RFC 1361** — Simple Network Time Protocol (SNTP) (1992)
- **RFC 1769** — Simple Network Time Protocol (SNTP) (1995)
- **RFC 2030** — Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI (1996)
- **RFC 4330** — Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI (2006)
## Security for NTP
- **RFC 5906** — NTPv4: Autokey Specification (2010)
- **RFC 8573** — Message Authentication Code for the Network Time Protocol (2019)
- **RFC 8915** — Network Time Security (NTS) for the Network Time Protocol (2020)
- **RFC 9109** — NTPv4: Port Randomization (2021)
## Updates / extensions to NTPv4 (RFC 5905)
- **RFC 7822** — NTPv4 Extension Fields (Updates RFC 5905) (2016)
- **RFC 9769** — NTP Interleaved Modes (Updates RFC 5905) (2025)
- **RFC 9748** — Updating the NTP Registries (2025)
## Operations / management / data models
- **RFC 8633 (BCP 223)** — Network Time Protocol Best Current Practices (2019)
- **RFC 5907** — Definitions of Managed Objects for NTPv4 (NTPv4 MIB) (2010)
- **RFC 9249** — A YANG Data Model for NTP (2022)
- **RFC 9327** — Control Messages Protocol for Use with NTPv4 (2022)
## Configuration / discovery (DHCP options)
- **RFC 4075** — SNTP Configuration Option for DHCPv6 (2005)
- **RFC 5908** — NTP Server Option for DHCPv6 (2010)
## Related NTP analysis / supporting documents (commonly cited)
- **RFC 1128** — Measured performance of the Network Time Protocol in the Internet system (1989)
- **RFC 1129** — Internet Time Synchronization: The Network Time Protocol (1989)
- **RFC 1165** — NTP over the OSI Remote Operations Service (1990)
- **RFC 1589** — A Kernel Model for Precision Timekeeping (1994)
- **RFC 1708** — NTP PICS PROFORMA (for NTPv3) (1994)
- **RFC 7384** — Security Requirements of Time Protocols in Packet Switched Networks (covers NTP among others) (2014)
- **RFC 8039** — Multipath Time Synchronization (includes NTP context) (2017)
- **RFC 7821** — UDP Checksum Complement in NTP (2016)
- **RFC 9523** — Secure Selection and Filtering Mechanism for NTP with Khronos (2024)