Stratum 2 ntp servers Jun 27, 2022 路 5. Naval Observatory, Washington, DC Synchronization: NTP V4 primary (USNO Master Clock H-masers) Access Policy: Open access for MIL, GOV, and other stratum 2 servers. Stratum 1 (primary) servers at the lowest level are directly synchronized to national time services. Either by using a GPS receiver or a radio referenced NTP server, a stratum 1 device is as accurate as you can get without having your own multi-million dollar atomic clock in the server room. The isolated server is Windows server 2008. Stratum 16 is used by NTP to indicate an unsynchronized device. 馃實 Free Public Stratum 2 Server NTP. atomic or GPS clocks. 20. The list of primary (stratum 1) and secondary (stratum 2) designates the NTP time servers available for public access under stated restrictions. 1 u 585 1024 377 22. Sharing time with other servers over a network introduces latencies. Mar 13, 2024 路 Quick definition: The NTP stratum is a hierarchical structure where each higher number represents another step from the NTP server. See full list on galsys. NTP Strata | Deployment Guide | Red Hat Enterprise Linux | 6 | Red Hat DocumentationNTP servers are classified according to their synchronization distance from the atomic clocks which are the source of the time signals. We kept sub-millisecond sync on 99% of our servers. Individual users should consult the public list of stratum 2 servers. org Europe — europe. As you progress through different strata there are network delays involved that reduce the accuracy of the NTP server in relation to UTC. Thanks! A stratum 2 NTP server receives its time through NTP from a stratum 1 NTP server, which in turn connects to the authoritative time source. 3 days ago 路 My NTP-Servers Part of ntppool. ca Nov 23, 2022 路 Stratum 1 (primary) servers at the lowest level are directly synchronized to national time services via satellite, radio or telephone modem. 6230 -195. 6) Location: Virginia Tech Computing Center, Blacksburg, VA, USA Synchronization: NTP V 3 secondary (Stratum 2), DEC 5810/ultrix Stratum2 servers derive their time from Stratum 1 servers via a network connection using the Network Time Protocol (NTP). Sep 13, 2023 路 The ntp master command configures the router as an NTP server, and the optional stratum-level parameter allows you to specify the stratum value for the router. It ensures accurate timekeeping between all devices and servers. Hence the word stratum is used when referring to a specific layer. 0801 Longitude: -114. A Stratum 2 device receives its time from a Stratum 1 Time Server. We will configure the two routers so that they will become NTP peers with one another. Stratum 2 again is slightly less accurate than stratum 1 because it is syncing its time against the stratum 1 source. Stratum 1 NTP Time Servers reference GPS Satellites directly and are considered the most accurate, because there is no network delay. Valid NTP stratum levels are in the range 1 to 15. 5 What is a stratum 1 Server? A server operating at stratum 1 belongs to the class of best NTP servers available, because it has a reference clock attached to it. This Product Note explains how to configure your Time Server for Stratum 2 operation. The device that has the most accuracy is the ‘reference’ clock—the clock with which the other devices on the system, such as workstations and servers, synchronize their time. The NTP subnet operates with a hierarchy of levels, where each level is assigned a number that is called the stratum. 31'N 45. Remember that network outages are at least Public NTP Time Servers The list of primary (stratum 1) and secondary (stratum 2) designates the NTP time servers available for public access under stated restrictions. Jan 6, 2020 路 Hi, Is there a way to specify a certain stratum when using the NTP pool? For example, if I wanted all pool members that are stratum 1, I could use stratum1. Please, send a mail to notify. Configuring for Stratum 2 operation is simple and described in the Stratum 2 Product Note. edu (128. navisdei. The lower a server is in the stratum hierarchy, the further away it is from the root time source, the poorer accuracy becomes. Jul 10, 2014 路 So it would look like: Corpoate NTP Server -> Isolated NTP Server -> Isolated Clients Our corporate NTP server is a stratum of 2. 196. org server 1. Nov 5, 2021 路 Time synchronization accuracy in Windows Server 2016 has been improved substantially, while maintaining full backwards NTP compatibility with older Windows versions. Stratum 2 (secondary) servers at the next higher level are synchronized to stratum 1 servers, and so on. Stratum 1 servers obtain time from hardware clocks and provide the most accurate time. Introduction This document defines the Network Time Protocol version 4 (NTPv4), which is widely used to synchronize system clocks among a set of distributed time servers and clients. 168. us. NTP was introduced in 1979 A quick and easy guide to understanding stratum clock systems, the different stratum levels, and how to optimize stratum systems for best performance. Therefore, peering Stratum 1 servers can dilute the precision of the servers. A group of NTP servers at the same Stratum level (Stratum 2, for example) are considered NTP Peers to each other. Sep 10, 2008 路 Stratum 1 time servers connected to a stratum 0 source, stratum 2 servers connected to stratum 1 and stratum 3 connected to stratum 2. org servers that are listed for Ubiquiti, and any other vendor that has servers defined in pool. Stratum 2 (secondary) servers at the next higher level are synchronized to stratum 1 servers and so on. We got by, just fine, syncing stratum 1 NTP into our internal network of stratum 2 servers. pub 2a01:4ff:f0:3be0::1 5. 1 u 881 1024 377 51. 35. Apr 4, 2005 路 Location: Brazilian Research Network/Rede Nacional de Pesquisa (RNP) Synchronization: NTP V4 Secondary (stratum 2), Sun SPARC10/Solaris, Service Area: Brazil Access Policy: Open access to stratum 2 and stratum 3 NTP servers. ntp-servers. 4233 -195. . GLN. Stratum 1 is a system that uses a stratum 0 time source as its time source (and is thus slightly less accurate than the stratum 0 time source). Understanding NTP Stratum Ranking and how this Affects Clock Accuracy The NTP protocol uses strata to indicate the expected accuracy of system clocks. ) will add an additional 1/2-100 ms of inaccuracy. 10. The NTP protocol does not allow clients to accept time from a Stratum 15 device, hence Stratum 15 is the lowest NTP Stratum. The algorithm is able to detect when a time source is likely to be extremely inaccurate, or insane, and to prevent synchronization in these cases, even if the inaccurate clock is at a lower stratum level. Normally a Stratum 2 computer will reference a number of Stratum 1 servers and use the NTP algorithm to gather the best data sample, dropping any Stratum 1 servers that seem obviously wrong. 161. Stratum values represent the distance between the NTP device and a reference clock (the most accurate time source). Apr 3, 2024 路 6. Unlike Stratum 1 servers, which are directly connected to ultra-precise Stratum0 reference clocks (e. 1. NTP never synchronizes to a system that is not in turn synchronized itself. S. But three is a good place to start, and you can progress to three-groups-of-three if you feel the need. org, 1. For example, stratum 2 servers synchronize stratum 3 servers, which in turn synchronize stratum 4 servers and so on. What hierarchical structure is used in the NTP protocol? Timing Knowledge Centre - Understanding NTP Stratum. United States — us. Each entry gives the host name, Internet address, approximate location and geographic coordinates (if available), synchronization source (stratum, type of radio or satellite receiver and host type), suggested service area Stratum 0 is the GPS Satellite itself. Jul 26, 2018 路 A Network Time Server with NTP synchronizes a network to highly accurate GPS atomic clocks. net Location: Saratov, Russian Federation (51. This is more than good enough for most services, even with distributed tracing requirements. org to find an NTP server (or 0. NTPv4 introduces new functionality to NTPv3, as described in [RFC1305], and A stratum 2 NTP server receives its time through NTP from a stratum 1 NTP server, which in turn connects to the authoritative time source. 12 . Synchronisation: NTP V3 (stratum 2), Digital AlphaServer 800 and AXP 3000's/Digital UNIX Service Area: New Zealand Access Policy: open access within New Zealand Contact: ntp@waikato. A stratum-3 server gets its time via NTP packet requests from a stratum-2 server, and so on. 173. org In most cases it's best to use pool. The following servers support only authenticated NTP requests using the symmetric key encryption method that is defined in the NTP documentation. It describes the core architecture, protocol, state machines, data structures, and algorithms. , atomic clocks or GPS systems), Stratum2 servers deliver exceptional timing precision over the network, making them highly scalable and versatile for distributed systems. NTP Servers at a higher Stratum level, on the other hand, are referred to as NTP Servers. Windows Time Service (w32time) – The built-in NTP service for Windows operating systems. g. Mar 12, 2025 路 OpenNTPD – A simpler and more secure NTP daemon developed by the OpenBSD project. They do not respond to requests for time in the DAYTIME or TIME formats and will not accept anonymous ftp connections. ntp Jul 12, 2013 路 Stratum 2 These are computers that send NTP requests to Stratum 1 servers (all other DC other then the PDC emulator). Sep 11, 2025 路 The best way to make a highly accurate stratum-1 NTP server is to connect the PPS signal to a software defined pin (SDP) on the NIC which is receiving requests and sending responses to NTP clients. org Germany — de. ucalgary. Oct 23, 2025 路 A server synchronized to a stratum N server automatically becomes stratum N+1. org config win10 config linux Mastodon Mar 27, 2019 路 In most cases the accuracy of the NTP secondary (stratum 2) servers is only slightly degraded relative to the primary servers and, as a group, the secondary servers may be just as reliable. NTP capsule summary Primary (stratum 1) servers synchronize to national time standards via radio, satellite and modem. First, at the topmost level, there is highly accurate time resources' ex. Oct 23, 2025 路 Stratum 2 servers synchronize stratum 3 servers, which in turn synchronize stratum 4 servers and so on. When using multiple servers with same stratum setting, the best practice to configure a preferred server, so NTP will attempt to use the preferred server as the primary NTP connection. org server 3. ac. co. A stratum 2 NTP server receives its time through NTP from a stratum 1 time server. Obviously you have some tolerance, or you would be buying GPS receivers and installing your own stratum-1 servers. GPS0. Read on for how and why to get this tool running. org de. ntp. be is a nice pool of four public no-notify stratum 2 servers run by a group of Belgian software defined radio enthusiasts:" Thank you, but they are actually 1 Stratum 1 server and 3 Stratum 2 servers. rnp. Nov 10, 2025 路 us. A stratum-2 server will have anywhere from 1/2 to 100 ms accuracy to UTC and each subsequent stratum layer (stratum-3, etc. ABOUT STRATUM 2 Configuring a Stratum 1 time server to fallback to Stratum 2 operation when it loses signal lock is a good alternative to peering. 4. Most sources are academic institutions or science-focused agencies using specialized hardware to maintain Stratum 1 accuracy. Sep 29, 2010 路 Stratum 1 devices are NTP time servers that get their source of time directly from these stratum 0 atomic clocks. Stratum-2 is an NTP client syncing from Stratum-1 and so on. A Large list of DNS and service checked Network Time Protocol Servers, in the United Kingdom RFC 5905 NTPv4 Specification June 2010 1. And so on. org USA — us. 0907 0. The servers are thought of as being arranged in layers, or strata, from 1 at the top down to 15. The higher stratum levels are separated from the Stratum-1 server over a network path; therefore a Stratum-2 server receives its time over a network link from a Stratum-1 server. Each of my high stratum NTP servers has a few public S1 NTP servers in its configuration so that hopefully even if the GPS does go nuts the other (public) servers prevent it from serving bad time. As accurate reference clocks are expensive, only a few of these servers are publicly available. NTP avoids synchronizing to a network device that may keep accurate time. heppen. org, etc if you need multiple server names). Sep 6, 2012 路 Timestamps generated by an EndRun Stratum 1 Time Server will typically have 10 microseconds accuracy to UTC. 198. Please notify us. 1 and R2 is an NTP client to NTP server 10. Before synchronizing, NTP compares the time reported by several network devices and does not synchronize with one that is significantly different, even if it is a stratum 1. 1 u 138 1024 377 48. Contact: ntp-admin@cais. Jul 24, 2024 路 A stratum server may also peer with other stratum servers at the same level to provide more stable and robust time for all devices in the peer group (for example a stratum 2 server can peer with other stratum 2 servers). 59'E), HSDN-D6 List of peers: remote refid st t when poll reach delay offset jitter =============================================================================== +194. GNSS. 65. Jul 23, 2025 路 Provides consistent timekeeping for file servers Working of NTP : NTP is a protocol that works over the application layer, it uses a hierarchical system of time resources and provides synchronization within the stratum servers. 71. org server 2. org To use this specific pool zone, add the following to your ntp. Location: Time Service Dept. timeserver. NTP Servers All of the following stratum 1 NTP servers are open to stratum 2 servers within the same time zone and to others by arrangement. A total of 15 synchronized stratum levels are possible, but each one introduces another layer of network delay, causing accuracy to decrease. , U. 96 us. 5202 2. ntp4. Stratum-1 would be a NTP client synchronising from a Stratum-0, usually a regular computer with regular computer hardware. conf file: server 0. org servers should be moved to the section for pool. 4574 4. pool. 15 us2. org 2. 1281 Synchronization: NTP V4 Primary (GPS clock), UltraSparc/Solaris Service Area: North America Access Policy: Open to stratum 2 time servers, others by arrangement. Meinberg NTP – A robust NTP distribution for Windows, based on the original ntpd. cc. In NTP Configuration, to set a Cisco device as NTP Server, we use “ ntp master stratum-level ” command on it. The system will try finding the closest 1 day ago 路 "ntp. Apr 4, 2005 路 Organization: Department of Computer Science, University of Calgary Location: Calgary, Alberta, Canada Geographic Coordinates: Latitude: 51. org 0. Mar 18, 2020 路 As smearing happens on many Stratum 2 servers at the same time, it’s important for the steps to be as similar as possible. 190. Contact: Shaun Laing (timemaster@cpsc. The stratum level is the reliability of the NTP Server. Learn about NTP server stratum, why it matters and how it ensures accurate timekeeping across networks. 22. vt. R1 is an NTP client to NTP server 10. pub 2a01:4f8:c012:e02e::1 88. Atomic Mar 14, 2024 路 NTP generally prefers lower stratum servers to higher stratum servers unless the lower stratum server time is significantly different. Stratum 2 Configuration "Smarter Timing Solutions" EndRun Technologies Network Time Servers are designed for Stratum 1 operation. all of the clients drop the packet because they say they fail "test 7" due to a stratum greater than 15. More complete synchronization systems, although lacking NTP's data analysis and clock disciplining algorithms, include the Unix daemon timed, which uses an election algorithm to appoint a server for all the clients; [22] and the Digital Time Synchronization Service (DTSS), which uses a hierarchy of servers similar to the NTP stratum model. nz vtserf. Sep 22, 2022 路 Stratum 2+ NTP servers have multiple potential sources of error, let's experiment with lowering them. A machine’s time can be synchronized directly with the Apr 23, 2014 路 In NTP, stratum 0 is by definition an accurate time source. Servers rely on the Network Time Protocol (NTP) to synchronize their clocks, ensuring uniformity across the network. 4 . In addition to having a precise and well-maintained and calibrated reference clock, a stratum 1 server should be highly available Oct 23, 2025 路 It is generally considered best practice NOT to peer stratum 1 NTP servers. In computing and IT, precision timing is crucial. org. 2. 0214 1. Each entry in the list details country code, state, host name, internet address, location and geographic coordinates, synchronisation source, access restrictions and maintainer. Our two routers, R1 and R2, are Stratum 2. com is a free public Stratum 2 NTP server that aggregates time signals from carefully selected sources across the globe—from the USA and Europe to China and Japan. Mar 8, 2019 路 In this post, we’ll discuss stratum clock systems and then explain what’s behind each of these stratum levels. org 1. br Supports following time protocols: - Simple Network Time Protocol (UDP/IP) 5 days ago 路 So, the amazon. 1 . The same is true for the pool. What is the rule of thumb for number of servers to synchronize to? It is entirely up to you and your tolerance for outages. 200. First, we will set the NTP server for the routers using the ‘ntp server’ command. Our isolated NTP server is a stratum of 15 and I can't figure out why. conf file of Server-A and adding a line such as this: Sep 7, 2020 路 Stratum 2 devices can function like a server by providing time to clients on stratum 3, and Stratum 3 can provide it to those on stratum 4, and so on. Smoother sine-curve smearing is also safer for the applications. pub 2a01:4ff:f0:bf2f::1 5. 34 Global — pool. Thus, a stratum-2 server gets its time via NTP packet requests from a stratum-1 server. Briefly, you must point Stratum 1 Server-A (for example) to Stratum 1 Server-B by editing the ntp. A list of stratum 1 and stratum 2 public NTP servers is maintained for public use under stated restrictions. Stratum 2 NTP Time Servers can still maintain accuracy within milliseconds of the authoritative time source. org or if I wanted stratum 2 servers, I could use stratum2. uk Mar 4, 2024 路 The NTP time server is used for reliable time synchronisation of a network. rqmsiam crjnwda dvwkhop yvxg gstjvsr ovsb mfk lfcaev jey yof vker nrzv ddnq sizih icja