Network Time Protocol (NTP) Parameters
Created
- 2010-03-25
Last Updated
- 2026-08-18
Available Formats
NTP Reference Identifier Codes
Registration Procedure(s)
- Specification Required
Expert(s)
- Kurt Kristof Teichel, Miroslav Lichvar, David Venhoek
Reference
- RFC 5905: Network Time Protocol Version 4: Protocol and Algorithms Specification
- RFC 9748: Updating the NTP Registries
Note
Codes beginning with the character "X" are reserved for experimentation and development. IANA cannot assign them.
Available Formats
| ID | Clock Source | Reference |
|---|---|---|
| GOES | Geosynchronous Orbit Environment Satellite | RFC 5905 |
| GPS | Global Position System | RFC 5905 |
| GAL | Galileo Positioning System | RFC 5905 |
| PPS | Generic pulse-per-second | RFC 5905 |
| IRIG | Inter-Range Instrumentation Group | RFC 5905 |
| WWVB | LF Radio WWVB Ft. Collins, CO 60 kHz | RFC 5905 |
| DCF | LF Radio DCF77 Mainflingen, DE 77.5 kHz | RFC 5905 |
| HBG | LF Radio HBG Prangins, HB 75 kHz | RFC 5905 |
| MSF | LF Radio MSF Anthorn, UK 60 kHz | RFC 5905 |
| JJY | LF Radio JJY Fukushima, JP 40 kHz, Saga, JP 60 kHz | RFC 5905 |
| LORC | MF Radio LORAN C station, 100 kHz | RFC 5905 |
| TDF | MF Radio Allouis, FR 162 kHz | RFC 5905 |
| CHU | HF Radio CHU Ottawa, Ontario | RFC 5905 |
| WWV | HF Radio WWV Ft. Collins, CO | RFC 5905 |
| WWVH | HF Radio WWVH Kauai, HI | RFC 5905 |
| NIST | NIST telephone modem | RFC 5905 |
| ACTS | NIST telephone modem | RFC 5905 |
| USNO | USNO telephone modem | RFC 5905 |
| PTB | European telephone modem | RFC 5905 |
| DFM | UTC(DFM) | DFM A/S; Jürgen Appel |
NTP Kiss-o'-Death Codes
Registration Procedure(s)
- Specification Required
Expert(s)
- Kurt Kristof Teichel, Miroslav Lichvar, David Venhoek
Reference
- RFC 5905: Network Time Protocol Version 4: Protocol and Algorithms Specification
- RFC 9748: Updating the NTP Registries
Note
Codes beginning with the character "X" are reserved for experimentation and development. IANA cannot assign them.
Available Formats
| ID | Meaning Source | Reference |
|---|---|---|
| ACST | The association belongs to a unicast server | RFC 5905 |
| AUTH | Server authentication failed | RFC 5905 |
| AUTO | Autokey sequence failed | RFC 5905 |
| BCST | The association belongs to a broadcast server | RFC 5905 |
| CRYP | Cryptographic authentication or identification failed | RFC 5905 |
| DENY | Access denied by remote server | RFC 5905 |
| DROP | Lost peer in symmetric mode | RFC 5905 |
| RSTR | Access denied due to local policy | RFC 5905 |
| INIT | The association has not yet synchronized for the first time | RFC 5905 |
| MCST | The association belongs to a dynamically discovered server | RFC 5905 |
| NKEY | No key found. Either the key was never installed or is not trusted | RFC 5905 |
| NTSN | Network Time Security (NTS) negative-acknowledgment (NAK) | RFC 8915, Section 5.7 |
| RATE | Rate exceeded. The server has temporarily denied access because the client exceeded the rate threshold | RFC 5905 |
| RMOT | Alteration of association from a remote host running ntpdc. | RFC 5905 |
| STEP | A step change in system time has occurred, but the association has not yet resynchronized | RFC 5905 |
NTP Extension Field Types
Registration Procedure(s)
- Specification Required
Expert(s)
- Kurt Kristof Teichel, Miroslav Lichvar, David Venhoek
Reference
- RFC 5905: Network Time Protocol Version 4: Protocol and Algorithms Specification
- RFC 5906: Network Time Protocol Version 4: Autokey Specification
- RFC 9748: Updating the NTP Registries
Note
Field Types in the range 0xF000 through 0xFFFF, inclusive, are reserved for experimentation and development. IANA cannot assign them. Both NTS Cookie and Autokey Message Request have the same Field Type; in practice this is not a problem as the field semantics will be determined by other parts of the message.
Note
The "Reserved for historic reasons" is for differences between the original documentation and implementation of Autokey and marks the erroneous values as reserved, in case there is an implementation that used the registered values instead of what the original implementation used.
Available Formats
| Field Type | Meaning | Reference |
|---|---|---|
| 0x0000 | Crypto-NAK; authentication failure | RFC 5905 |
| 0x0002 | Reserved for historic reasons | RFC 9748 |
| 0x0102 | Reserved for historic reasons | RFC 9748 |
| 0x0104 | Unique Identifier | RFC 8915, Section 5.3 |
| 0x010A | Network Correction | RFC 10030 |
| 0x0200 | No-Operation Request | RFC 5906 |
| 0x0201 | Association Message Request | RFC 5906 |
| 0x0202 | Certificate Message Request | RFC 5906 |
| 0x0203 | Cookie Message Request | RFC 5906 |
| 0x0204 | Autokey Message Request | RFC 5906 |
| 0x0204 | NTS Cookie | RFC 8915, Section 5.4 |
| 0x0205 | Leapseconds Message Request | RFC 5906 |
| 0x0206 | Sign Message Request | RFC 5906 |
| 0x0207 | IFF Identity Message Request | RFC 5906 |
| 0x0208 | GQ Identity Message Request | RFC 5906 |
| 0x0209 | MV Identity Message Request | RFC 5906 |
| 0x0302 | Reserved for historic reasons | RFC 9748 |
| 0x0304 | NTS Cookie Placeholder | RFC 8915, Section 5.5 |
| 0x0402 | Reserved for historic reasons | RFC 9748 |
| 0x0404 | NTS Authenticator and Encrypted Extension Fields | RFC 8915, Section 5.6 |
| 0x0502 | Reserved for historic reasons | RFC 9748 |
| 0x0602 | Reserved for historic reasons | RFC 9748 |
| 0x0702 | Reserved for historic reasons | RFC 9748 |
| 0x0802 | Reserved for historic reasons | RFC 9748 |
| 0x0902 | Reserved for historic reasons | RFC 9748 |
| 0x2005 | UDP Checksum Complement | RFC 7821 |
| 0x8002 | Reserved for historic reasons | RFC 9748 |
| 0x8102 | Reserved for historic reasons | RFC 9748 |
| 0x8200 | No-Operation Response | RFC 5906 |
| 0x8201 | Association Message Response | RFC 5906 |
| 0x8202 | Certificate Message Response | RFC 5906 |
| 0x8203 | Cookie Message Response | RFC 5906 |
| 0x8204 | Autokey Message Response | RFC 5906 |
| 0x8205 | Leapseconds Message Response | RFC 5906 |
| 0x8206 | Sign Message Response | RFC 5906 |
| 0x8207 | IFF Identity Message Response | RFC 5906 |
| 0x8208 | GQ Identity Message Response | RFC 5906 |
| 0x8209 | MV Identity Message Response | RFC 5906 |
| 0x8302 | Reserved for historic reasons | RFC 9748 |
| 0x8402 | Reserved for historic reasons | RFC 9748 |
| 0x8502 | Reserved for historic reasons | RFC 9748 |
| 0x8602 | Reserved for historic reasons | RFC 9748 |
| 0x8702 | Reserved for historic reasons | RFC 9748 |
| 0x8802 | Reserved for historic reasons | RFC 9748 |
| 0x8902 | Reserved for historic reasons | RFC 9748 |
| 0xC002 | Reserved for historic reasons | RFC 9748 |
| 0xC102 | Reserved for historic reasons | RFC 9748 |
| 0xC200 | No-Operation Error Response | RFC 5906 |
| 0xC201 | Association Message Error Response | RFC 5906 |
| 0xC202 | Certificate Message Error Response | RFC 5906 |
| 0xC203 | Cookie Message Error Response | RFC 5906 |
| 0xC204 | Autokey Message Error Response | RFC 5906 |
| 0xC205 | Leapseconds Message Error Response | RFC 5906 |
| 0xC206 | Sign Message Error Response | RFC 5906 |
| 0xC207 | IFF Identity Message Error Response | RFC 5906 |
| 0xC208 | GQ Identity Message Error Response | RFC 5906 |
| 0xC209 | MV Identity Message Error Response | RFC 5906 |
| 0xC302 | Reserved for historic reasons | RFC 9748 |
| 0xC402 | Reserved for historic reasons | RFC 9748 |
| 0xC502 | Reserved for historic reasons | RFC 9748 |
| 0xC602 | Reserved for historic reasons | RFC 9748 |
| 0xC702 | Reserved for historic reasons | RFC 9748 |
| 0xC802 | Reserved for historic reasons | RFC 9748 |
| 0xC902 | Reserved for historic reasons | RFC 9748 |
| 0xF000-0xFFFF | Reserved for Private or Experimental Use | RFC 9748 |
Contact Information
| Name | Organization | Contact URI | Last Updated |
|---|---|---|---|
| DFM A/S | https://dfm.dk | 2023-05-03 | |
| Jürgen Appel | DFM A/S | jap&dfm.dk | 2023-05-03 |