DOCSLIB.ORG

NTP Release 4.2.8P3

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
NTP Release 4.2.8P3 NTP Release 4.2.8p3 September 07, 2015 CONTENTS 1 The Network Time Protocol (NTP) Distribution1 1.1 The Handbook..............................................1 1.2 Building and Installing NTP.......................................2 1.3 Resolving Problems...........................................2 1.4 Further Information...........................................2 2 Build and Install 3 2.1 Quick Start................................................3 2.2 Building and Installing the Distribution.................................4 2.3 Build Options...............................................5 2.4 Debugging Reference Clock Drivers...................................5 2.5 NTP Debugging Techniques.......................................6 2.6 Hints and Kinks............................................. 10 2.7 NTP Bug Reporting Procedures..................................... 10 3 Program Manual Pages 11 3.1 ntpd - Network Time Protocol (NTP) Daemon............................. 11 3.2 ntpq - standard NTP query program.................................. 14 3.3 ntpdc - special NTP query program.................................. 22 3.4 ntpdate - set the date and time via NTP................................ 28 3.5 ntp-wait - waits until ntpd is in synchronized state......................... 30 3.6 sntp - Simple Network Time Protocol (SNTP) Client......................... 30 3.7 ntptrace - trace a chain of NTP servers back to the primary source................. 33 3.8 tickadj - set time-related kernel variables.............................. 33 3.9 ntptime - read and set kernel time variables............................. 35 3.10 ntp-keygen - generate public and private keys............................ 35 3.11 ntpdsim - Network Time Protocol (NTP) simulator.......................... 40 3.12 ntpdsim - Network Time Protocol (NTP) Simulator......................... 41 4 Handbook Pages 45 4.1 NTP Version 4 Release Notes...................................... 45 4.2 Command Index............................................. 48 4.3 Access Control Support......................................... 50 4.4 Association Management........................................ 50 4.5 Authentication Support.......................................... 53 4.6 Performance Metrics........................................... 55 4.7 Rate Management and the Kiss-o’-Death Packet............................ 58 4.8 Reference Clock Support......................................... 60 5 Client and Server Configuration 63 5.1 Automatic Server Discovery Schemes.................................. 63 i 5.2 Server Commands and Options..................................... 66 5.3 Access Control Commands and Options................................. 69 5.4 Authentication Commands and Options................................. 71 5.5 Reference Clock Commands and Options................................ 72 5.6 Miscellaneous Commands and Options................................. 73 5.7 Monitoring Commands and Options................................... 78 6 Reference Clock Support 83 6.1 External Clock Discipline and the Local Clock Driver......................... 83 6.2 How to Write a Reference Clock Driver................................. 84 6.3 NTP PARSE clock data formats..................................... 87 6.4 How to build new PARSE clocks.................................... 93 7 Reference Clock Audio Drivers 97 7.1 Reference Clock Audio Drivers..................................... 97 7.2 IRIG Audio Decoder........................................... 99 7.3 Radio CHU Audio Demodulator/Decoder................................ 102 7.4 Radio WWV/H Audio Demodulator/Decoder.............................. 106 8 Miscellaneous Pages 115 8.1 Configuration File Definition (Advanced)................................ 115 8.2 Event Messages and Status Words.................................... 119 8.3 Kernel Model for Precision Timekeeping................................ 124 8.4 ntpd System Log Messages....................................... 124 8.5 PPSAPI Interface for Precision Time Signals.............................. 127 8.6 Pulse-Per-Second (PPS) Signal Interfacing............................... 128 8.7 Historical Notes on NTP Upgrades................................... 130 8.8 Copyright Notice............................................. 134 9 Special Topics 139 9.1 How NTP Works............................................. 139 9.2 Mitigation Rules and the prefer Keyword.............................. 141 9.3 Autokey Public-Key Authentication................................... 144 9.4 Orphan Mode............................................... 151 9.5 NTP Interleaved Modes......................................... 153 9.6 The Huff-n’-Puff Filter.......................................... 153 9.7 Clock Filter Algorithm.......................................... 154 9.8 Clock Select Algorithm......................................... 157 9.9 Clock Cluster Algorithm......................................... 158 9.10 Mitigation Rules and the prefer Keyword.............................. 160 9.11 Clock Discipline Algorithm....................................... 163 9.12 Poll Process............................................... 166 9.13 Clock State Machine........................................... 166 9.14 Leap Second Processing......................................... 168 10 Reference Clock Drivers 171 10.1 Undisciplined Local Clock........................................ 171 10.2 PSTI/Traconex 1020 WWV/WWVH Receiver............................. 172 10.3 Spectracom WWVB/GPS Receivers................................... 173 10.4 TrueTime GPS/GOES/OMEGA/WWV Receivers............................ 175 10.5 IRIG Audio Decoder........................................... 177 10.6 Radio CHU Audio Demodulator/Decoder................................ 180 10.7 Generic Reference Driver........................................ 184 10.8 Magnavox MX4200 GPS Receiver................................... 192 10.9 Austron 2200A/2201A GPS Receivers................................. 193 ii 10.10 Arbiter 1088A/B GPS Receiver..................................... 194 10.11 KSI/Odetics TPRO/S IRIG Interface................................... 196 10.12 bc635VME/bc350VXI Time and Frequency Processor......................... 197 10.13 NIST/USNO/PTB Modem Time Services................................ 198 10.14 Heath WWV/WWVH Receiver..................................... 200 10.15 Generic NMEA GPS Receiver...................................... 201 10.16 PPS Clock Discipline.......................................... 205 10.17 Hewlett Packard 58503A GPS Receiver and HP Z3801A........................ 207 10.18 Arcron MSF Receiver.......................................... 208 10.19 Shared Memory Driver.......................................... 213 10.20 Trimble Palisade and Thunderbolt Receivers.............................. 217 10.21 Motorola Oncore GPS receiver..................................... 228 10.22 Rockwell Jupiter GPS receiver...................................... 230 10.23 Chrono-log K-series WWVB receiver.................................. 231 10.24 Dumb Clock............................................... 231 10.25 Ultralink Clock.............................................. 232 10.26 Conrad parallel port radio clock..................................... 234 10.27 Radio WWV/H Audio Demodulator/Decoder.............................. 235 10.28 Forum Graphic GPS Dating station................................... 242 10.29 hopf Serial Line Receivers (6021 and kompatible)........................... 243 10.30 hopf PCI-Bus Receiver (6039 GPS/DCF77)............................... 245 10.31 JJY Receivers.............................................. 246 10.32 Zyfer GPStarplus Receiver........................................ 251 10.33 RIPE NCC interface for Trimble Palisade................................ 252 10.34 NeoClock4X - DCF77 / TDF serial line receiver............................ 254 10.35 Spectracom TSYNC PCI......................................... 255 10.36 GPSD NG client driver.......................................... 255 10.37 MX4200 Receiver Data Format..................................... 260 10.38 Motorola ONCORE - The Shared Memory Interface.......................... 267 10.39 European Automated Computer Time Services............................. 271 Index 273 iii iv CHAPTER ONE THE NETWORK TIME PROTOCOL (NTP) DISTRIBUTION Note: The NTP Version 4 software contained in this distribution is available without charge under the conditions set forth in the Copyright Notice. Important: It is very important that readers understand that the NTP document collection began 25 years ago and remains today a work in progress. It has evolved as new features were invented and old features retired. It has been widely copied, cached and morphed to other formats, including man pages, with varying loss of fidelity. However, these HTML pages are the ONLY authoritative and definitive reference. Readers should always use the collection that comes with the distribution they use. A copy of the online collection at www.ntp.org is normally included in the most recent snapshot, but might not agree with an earlier snapshot or release version. This distribution is an implementation of RFC 5905 “Network Time Protocol Version 4: Protocol and Algorithms Specification”. NTP is widely used to synchronize a computer to Internet time servers or other sources, such as a radio or satellite receiver or telephone modem service. It can also be used as a server for dependent
Load more

Recommended publications
  • Webinar PPT/Slides
    3/16/2021 Child Trauma, Parenting, & Challenging Behaviors Melissa Bernstein, PhD 1 The impact of trauma on parenting Functional Assessment- what’s going on?! Overview The importance of relationships Strategies to shape behavior 2 THE IMPACT OF TRAUMA ON PARENTING 3 1 3/16/2021 BEHAVIOR PROBLEMS AND CHILDREN What are the most disruptive child behaviors? 4 What Does Ideal Parenting Look Like? Nurturing Appropriate Interactions Limits 5 What Can Happen to Balance after Trauma? High Nurturing Low Limits 6 2 3/16/2021 What Can Happen to Balance after Trauma? High Limits Low Nurturing 7 THE IMPORTANCE OF ASSESSMENT IN MANAGING CHALLENGING BEHAVIOR 8 • The body’s ‘alarm’ system is broken after a trauma Trauma Reactions • The body responds in one of three ways to promote and Misbehavior ‘survival’ • This makes it harder for children to regulate their behavior FightFlight Freeze 9 3 3/16/2021 Clues That a Child is Stuck in Fight/Flight/Freeze • Extreme emotions • Behavior feels like its out of the blue • Big response over very minor issue • Happens quickly (0 to 60) • Child is unable to calm down • Doesn’t respond to reasoning • Distress may last a long time • Apologetic later 10 What is the function of this behavior? 11 Applying Skills to Trauma Reactions Create Reflect Offer Allow Create a Briefly reflect Offer to do a Allow child sense of emotion favorite time to calm safety • Tell child you can coping skill • This means back • Stand a few feet see he/she/they together away and be away from child is feeling upset quiet! Less and you are •
    [Show full text]
  • Option 33: Dual Internal NTP Server Setup and Operation Guidelines
    -DISCONTINUED PRODUCT- Option 33: Dual Internal NTP Server Setup and Operation Guidelines Document No. PD0042100D – April 2009 Arbiter Systems, Inc. 1324 Vendels Circle, Suite 121 Paso Robles, CA 93446 U.S.A. (805) 237-3831, (800) 321-3831 http://www.arbiter.com mailto: [email protected] 1 Option 33: Dual Internal NTP Server 1.1 General Description Option 33, Dual Internal Network Time Protocol (NTP) Server, is used in the Arbiter Systems line of 19-inch, rack mount Satellite-Controlled Clocks. This option comes with a six-foot phone cable and RJ-11 to DB-9F adapter for connecting to the RS-232, or NTP Setup, port. 1.1.1 Option 33 Option 33 allows the clock to act as time server over an Ethernet network using the network time protocol operating in server mode - symmetric operation modes are not supported. Time is distributed over the network interface to computers, controllers and other equipment needing the correct time. Option 33 understands NTP Version 1, Version 2, and Version 3 frames, and optionally supports authentication via DES and MD5 cryptographic checksums. If authentication is not used, the controller can typically be used for hundreds of clients without overloading it. Authentication requires typically 40 ms for checking and generating the cryptograms, which is covered and averaged out by the protocol. Option 33 supports full SNTP and all NTP functions required for reliable server operation. Functions not required for server operation are not implemented. 1.1.2 Hardware Configuration. Option 33 consists of two building blocks; two OEM NTP modules and an interface to the GPS clock.
    [Show full text]
  • Cisco Telepresence TC Software Licensing Information (TC4.1)
    Cisco TelePresence TC Software License information guide TC Software FEBRUARY 2011 Legal information and third party copyright and licenses For Cisco TelePresence products using TC software D14767.02 License Information for products using TC Software, TC4 February 2011. 1 © 2010-2011 Cisco Systems, Inc. All rights reserved. www.cisco.com Cisco TelePresence TC Software License information guide ipcalc-1.3, ipcalc-license ...................................................................................... 16 TA - ToC - Hidden Table of Contents iproute-2.6.26, GPLv2 .......................................................................................16 What’stext anchor in iptables-1.4.28, GPLv2......................................................................................16 About this guide ..............................................................................................................4 iputils-s20071127, iputils-bsd-license .................................................... 16 The products covered by this guide: .....................................................4 jpeg lib, jpeg-license ................................................................................................ 17 this guide? User documentation .............................................................................................4 Kmod-*, GPLv2 ........................................................................................................19 Software download ................................................................................................4
    [Show full text]
  • Mike Zornek • March 2020
    Working with Time Zones Inside a Phoenix App Mike Zornek • March 2020 Terminology Layers of Wall Time International Atomic Time (ITA) Layers of Wall Time Universal Coordinated Time (UTC) International Atomic Time (ITA) Layers of Wall Time Universal Coordinated Time (UTC) Leap Seconds International Atomic Time (ITA) Layers of Wall Time Standard Time Universal Coordinated Time (UTC) Leap Seconds International Atomic Time (ITA) Layers of Wall Time Standard Time Time Zone UTC Offset Universal Coordinated Time (UTC) Leap Seconds International Atomic Time (ITA) Layers of Wall Time Wall Time Standard Time Time Zone UTC Offset Universal Coordinated Time (UTC) Leap Seconds International Atomic Time (ITA) Layers of Wall Time Wall Time Standard Offset Standard Time Time Zone UTC Offset Universal Coordinated Time (UTC) Leap Seconds International Atomic Time (ITA) Things Change Wall Time Standard Offset Politics Standard Time Time Zone UTC Offset Politics Universal Coordinated Time (UTC) Leap Seconds Celestial Mechanics International Atomic Time (ITA) Things Change Wall Time Standard Offset changes ~ 2 / year Standard Time Time Zone UTC Offset changes ~ 10 / year Universal Coordinated Time (UTC) 27 changes so far Leap Seconds last was in Dec 2016 ~ 37 seconds International Atomic Time (ITA) "Time Zone" How Elixir Represents Time Date Time year hour month minute day second nanosecond NaiveDateTime Date Time year hour month minute day second nanosecond DateTime time_zone NaiveDateTime utc_offset std_offset zone_abbr Date Time year hour month minute day second
    [Show full text]
  • OSS Disclosure
    Tape Automation Scalar i500, Firmware Release I8.2.2 (645G) Open Source Software Licenses Open Source Software (OSS) Licenses for: Scalar i500 Firmware Release I8.2.2 (645G). The firmware/software contained in the Scalar i500 is an aggregate of vendor proprietary pro- grams as well as third party programs, including Open Source Software (OSS). Use of OSS is subject to designated license terms and the following OSS license disclosure lists all open source components and applicable licenses that are part of the tape library firmware. All software that is designated as OSS may be copied, distributed, and/or modified in accordance with the terms and conditions of its respective license(s). Additionally, for some OSS you are entitled to obtain the corresponding OSS source files as required by the respective and applicable license terms. While GNU General Public License ("GPL") and GNU Lesser General Public Li- cense ("LGPL") licensed OSS requires that the sources be made available, Quantum makes all tape library firmware integrated OSS source files, whether licensed as GPL, LGPL or otherwise, available upon request. Please refer to the Scalar i500 Open Source License CD (part number 3- 03679-xx) when making such request. For contact information, see Getting More Information. LTO tape drives installed in the library may also include OSS components. For a complete list- ing of respective OSS packages and applicable OSS license information included in LTO tape drives, as well as instructions to obtain source files pursuant to applicable license requirements, please reference the Tape Automation disclosure listings under the Open Source Information link at www.quantum.com/support.
    [Show full text]
  • Creating a Mesh Sensor Network Using Raspberry Pi and Xbee Radio Modules
    Creating a mesh sensor network using Raspberry Pi and XBee radio modules By Michael Forcella In Partial Fulfillment of the Requirement for the Degree of MASTER OF SCIENCE In The Department of Computer Science State University of New York New Paltz, NY 12561 May 2017 Creating a mesh sensor network using Raspberry Pi and XBee radio modules Michael Forcella State University of New York at New Paltz _________________________________ We the thesis committee for the above candidate for the Master of Science degree, hereby recommend acceptance of this thesis. ______________________________________ David Richardson, Thesis Advisor Department of Biology, SUNY New Paltz ______________________________________ Chirakkal Easwaran, Thesis Committee Member Department of Computer Science, SUNY New Paltz ______________________________________ Hanh Pham, Thesis Committee Member Department of Computer Science, SUNY New Paltz Approved on __________________ Submitted in partial fulfillment for the requirements for the Master of Science degree in Computer Science at the State University of New York at New Paltz ABSTRACT A mesh network is a type of network topology in which one or more nodes are capable of relaying data within the network. The data is relayed by the router nodes, which send the messages via one or more 'hops' until it reaches its intended destination. Mesh networks can be applied in situations where the structure or shape of the network does not permit every node to be within range of its final destination. One such application is that of environmental sensing. When creating a large network of sensors, however, we are often limited by the cost of such sensors. This thesis presents a low-cost mesh network framework, to which any number of different sensors can be attached.
    [Show full text]
  • Operation Guide 3448
    MO1611-EA © 2016 CASIO COMPUTER CO., LTD. Operation Guide 3448 ENGLISH Congratulations upon your selection of this CASIO watch. Warning ! • The measurement functions built into this watch are not intended for taking measurements that require professional or industrial precision. Values produced by this watch should be considered as reasonable representations only. • Note that CASIO COMPUTER CO., LTD. assumes no responsibility for any damage or loss suffered by you or any third party arising through the use of your watch or its malfunction. E-1 About This Manual • Keep the watch away from audio speakers, magnetic necklaces, cell phones, and other devices that generate strong magnetism. Exposure to strong • Depending on the model of your watch, display text magnetism can magnetize the watch and cause incorrect direction readings. If appears either as dark figures on a light background, or incorrect readings continue even after you perform bidirectional calibration, it light figures on a dark background. All sample displays could mean that your watch has been magnetized. If this happens, contact in this manual are shown using dark figures on a light your original retailer or an authorized CASIO Service Center. background. • Button operations are indicated using the letters shown in the illustration. • Note that the product illustrations in this manual are intended for reference only, and so the actual product may appear somewhat different than depicted by an illustration. E-2 E-3 Things to check before using the watch Contents 1. Check the Home City and the daylight saving time (DST) setting. About This Manual …………………………………………………………………… E-3 Use the procedure under “To configure Home City settings” (page E-16) to configure your Things to check before using the watch ………………………………………… E-4 Home City and daylight saving time settings.
    [Show full text]
  • Netflix and Twitch Traffic Characterization
    University of Calgary PRISM: University of Calgary's Digital Repository Graduate Studies The Vault: Electronic Theses and Dissertations 2015-09-30 NetFlix and Twitch Traffic Characterization Laterman, Michel Laterman, M. (2015). NetFlix and Twitch Traffic Characterization (Unpublished master's thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/27074 http://hdl.handle.net/11023/2562 master thesis University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. Downloaded from PRISM: https://prism.ucalgary.ca UNIVERSITY OF CALGARY NetFlix and Twitch Traffic Characterization by Michel Laterman A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE GRADUATE PROGRAM IN COMPUTER SCIENCE CALGARY, ALBERTA SEPTEMBER, 2015 c Michel Laterman 2015 Abstract Streaming video content is the largest contributor to inbound network traffic at the University of Calgary. Over five months, from December 2014 { April 2015, over 2.7 petabytes of traffic on 49 billion connections was observed. This thesis presents traffic characterizations for two large video streaming services, namely NetFlix and Twitch. These two services contribute a significant portion of inbound bytes. NetFlix provides TV series and movies on demand. Twitch offers live streaming of video game play. These services share many characteristics, including asymmetric connections, content delivery mechanisms, and content popularity patterns.
    [Show full text]
  • Reference Manual GUI Graphical User Interface EAGLE One Rel. 5.3
    Reference Manual GUI Graphical User Interface Industrial Ethernet Firewall EAGLE One RM GUI EAGLE One Technical Support Release 5.3.0 09/2013 https://hirschmann-support.belden.eu.com The naming of copyrighted trademarks in this manual, even when not specially indicated, should not be taken to mean that these names may be considered as free in the sense of the trademark and tradename protection law and hence that they may be freely used by anyone. © 2013 Hirschmann Automation and Control GmbH Manuals and software are protected by copyright. All rights reserved. The copying, reproduction, translation, conversion into any electronic medium or machine scannable form is not permitted, either in whole or in part. An exception is the preparation of a backup copy of the software for your own use. For devices with embedded software, the end-user license agreement on the enclosed CD/DVD applies. The performance features described here are binding only if they have been expressly agreed when the contract was made. This document was produced by Hirschmann Automation and Control GmbH according to the best of the company's knowledge. Hirschmann reserves the right to change the contents of this document without prior notice. Hirschmann can give no guarantee in respect of the correctness or accuracy of the information in this document. Hirschmann can accept no responsibility for damages, resulting from the use of the network components or the associated operating software. In addition, we refer to the conditions of use specified in the license contract. You can get the latest version of this manual on the Internet at the Hirschmann product site (www.hirschmann.com).
    [Show full text]
  • Network Time Protocol (NTP) General Overview
    Network Time Protocol (NTP) General Overview David L. Mills University of Delaware http://www.eecis.udel.edu/~mills mailto:[email protected] alautun, Maya glyph 2-Aug-04 1 Introduction z Network Time Protocol (NTP) synchronizes clocks of hosts and routers in the Internet. z NIST estimates 10-20 million NTP servers and clients deployed in the Internet and its tributaries all over the world. Every Windows/XP has an NTP client. z NTP provides nominal accuracies of low tens of milliseconds on WANs, submilliseconds on LANs, and submicroseconds using a precision time source such as a cesium oscillator or GPS receiver. z NTP software has been ported to almost every workstation and server platform available today - from PCs to Crays - Unix, Windows, VMS and embedded systems, even home routers. z The NTP architecture, protocol and algorithms have been evolved over the last two decades to the latest NTP Version 4 described in this and related briefings. 2-Aug-04 2 The Sun never sets on NTP z NTP is argueably the longest running, continuously operating, ubiquitously available protocol in the Internet – USNO and NIST, as well as equivalents in other countries, provide multiple NTP primary servers directly synchronized to national standard cesium clock ensembles and GPS – Over 230 Internet primary serversare in Australia, Canada, Chile, France, Germany, Isreal, Italy, Holland, Japan, Norway, Sweden, Switzerland, UK, and US. z Well over a million Internet servers and clients all over the world – National and regional service providers BBN, MCI, Sprint, Alternet, etc. – Agencies and organizations: US Weather Service, US Treasury Service, IRS, PBS, Merrill Lynch, Citicorp, GTE, Sun, DEC, HP, etc.
    [Show full text]
  • GLONASS Time. 2. Generation of System Timescale
    GLONASS TIME SCALE DESCRIPTION Definition of System 1. System timescale: GLONASS Time. 2. Generation of system timescale: on the basis of time scales of GLONASS Central Synchronizers (CS). 3. Is the timescale steered to a reference UTC timescale: Yes. a. To which reference timescale: UTC(SU), generated by State Time and Frequency Reference (STFR). b. Whole second offset from reference timescale: 10800 s (03 hrs 00 min 00 s). tGLONASS =UTC (SU ) + 03 hrs 00 min c. Maximum offset (modulo 1s) from reference timescale: 660 ns (probability 0.95) – in 2014; 4 ns (probability 0.95) – in 2020. 4. Corrections to convert from satellite to system timescale: SVs broadcast corrections τn(tb) and γn(tb) in L1, L2 frequency bands for 30-minute segments of prediction interval. a. Type of corrections given; include statement on relativistic corrections: Linear coefficients broadcast in operative part of navigation message for each SV (in accordance with GLONASS ICD). Periodic part of relativistic corrections taking into account the deviation of individual SVs orbits from GLONASS nominal orbits is incorporated in calculation of broadcast corrections to convert from satellite timescale to GLONASS Time. b. Specified accuracy of corrections to system timescale: The accuracy of calculated offset between SV timescale and GLONASS Time – 5,6 ns (rms). c. Location of corrections in broadcast messages: L1/L2 - τn(t b) – line 4, bits 59 – 80 of navigation frame; - γn(t b) - line 3, bits 69 – 79 of navigation frame. d. Equation to correct satellite timescale to system timescale: L1/L2 tGLONASS = t +τ n (tb ) − γ n (tb )( t − tb ) where t - satellite time; τn(t b), γn(tb) - coefficients of frequency/time correction; tb - time of locking frequency/time parameters.
    [Show full text]
  • Which Time Server Option Is Best for Synchronizing Your Clocks
    WHICH TIME SERVER OPTION IS BEST FOR SYNCHRONIZING YOUR CLOCKS? Any electronic device that automatically displays REGARDING MASTER the current local time – your clocks, phone, tablet, TIME CONTROLLERS computer and even most TVs – has to pull that time from a time server. AND The time server acts as a messenger of sorts; IP NETWORK CLOCKS it reads the time from a reference clock and distributes that information via a computer network (ETHERNET OR WI-FI) to your device when the device requests it. The time server could be a local network time server or an internet time server. SNTP, or Simple Network Time Protocol, is an internet standard protocol that allows a clock or device to contact a server and get the current time. It’s a simplification of the more robustNTP (Network Time Protocol) and is used in most embedded devices and computers. Once the device receives the current Coordinated Universal Time (UTC), the device applies offsets such as time zone or daylight saving time considerations, as well as the time spent on the network retrieving the time, before displaying the accurate local time. January 2018 AMERICAN TIME WHITE PAPER BY: MAX BLOM When it comes to syncing time for your organization’s clocks, you have 3 options: Let’s take a look at how each of these options work, their pros and cons, and our recommendation. Port 123 is reserved specifically for External Server IP Address NTP/SNTP communication 1 The NIST – the U.S. Department of Commerce’s National Institute of Standards and Technology – is the primary source for synchronizing time systems in the U.S.
    [Show full text]