time sources : Java Glossary

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time sources
Pacific Daylight Time

In our technological world there are many ways you can get the current time and date. Here is an eclectic list of time sources:

  1. From GPS satellites. GPS (Global Positioning System) provides a most excellent time source since it naturally compensates for propagation delay and is immune to network congestion and weather.
  2. setclock icon  SetClock is a Java Applet you can run on your PC (Personal Computer). It will get the accurate time from an atomic clock on the web provided by pool.ntp.org.
  3. From an atomic clock timeserver on the web using NTP NTP (Network Time Protocol). Timeservers come is various grades of accuracy. You are not supposed to pester the very accurate ones. They are for the secondary servers.
    NTP Time Servers
    Where Server IP (Internet Protocol) Can Use
    Without
    Notification
    AEae.pool.ntp.org87.201.239.3
    AMntp.adc.am91.103.24.10
    AOao.pool.ntp.org196.49.6.67
    ARtick.nap.com.ar200.10.140.1
    ARtock.nap.com.ar200.10.140.1
    ATat.pool.ntp.org80.92.126.65
    AUau.pool.ntp.org130.102.128.23
    AUntp.sjkwi.com.au203.206.185.142
    AUntp.tourism.wa.gov.au203.161.12.165
    AUntp1.tpg.com.au203.12.160.2
    AUntp2.tpg.com.au203.26.24.6
    Africaafrica.pool.ntp.org41.73.42.10
    Asiaasia.pool.ntp.org91.201.214.3
    BAba.pool.ntp.org195.222.33.219
    BDbd.pool.ntp.org114.130.13.6
    BEbe.pool.ntp.org51.255.138.215
    BEntp1.belbone.be195.13.23.5
    BEntp2.belbone.be195.13.1.153
    BGbg.pool.ntp.org46.40.123.212
    BRa.ntp.br200.160.0.8
    BRb.ntp.br200.189.40.8
    BRbr.pool.ntp.org192.155.90.13
    BRc.ntp.br200.192.232.8
    BRntp.cais.rnp.br200.144.121.33
    BRntp.pads.ufrj.br146.164.48.1
    BRntp.pop-pr.rnp.br200.19.74.21
    BSbs.pool.ntp.org208.87.33.150
    BYby.pool.ntp.org31.130.200.2
    CAca.pool.ntp.org70.79.92.55
    CAntp.cpsc.ucalgary.ca136.159.2.1
    CAntp1.cmc.ec.gc.ca205.189.10.21
    CAntp1.linuxhosted.ca72.20.40.62
    CAntp2.cmc.ec.gc.ca205.189.10.22
    CAntp2.linuxhosted.ca72.20.40.62
    CAntp3.linuxhosted.ca72.20.40.62
    CA NRCtime.chu.nrc.ca209.87.233.53
    CA NRCtime.nrc.ca132.246.11.229
    CA SK Reginatimelord.uregina.ca142.3.100.15
    CHb.ntp.madduck.net130.60.157.243
    CHc.ntp.madduck.net77.109.139.83
    CHch.pool.ntp.org130.60.204.10
    CHclock.tix.ch192.33.96.102
    CHntp.favey.ch195.34.89.227
    CHntp.metas.ch162.23.41.10
    CHntp11.metas.ch162.23.41.55
    CHntp12.metas.ch162.23.41.56
    CHtack.meteonews.ch78.46.52.71
    CHtick.meteonews.ch91.195.238.4
    CLcl.pool.ntp.org200.89.75.198
    CNt1.hshh.org208.80.96.70
    CNt2.hshh.org67.18.187.111
    CNt3.hshh.org199.182.221.110
    CRcr.pool.ntp.org190.106.66.11
    CZcz.pool.ntp.org212.96.168.167
    CZntp.cgi.cz178.238.36.117
    CZntp.globe.cz81.95.103.173
    CZntp.ujf.cas.cz147.231.100.5
    DEa.ntp.madduck.net188.174.253.163
    DEde.pool.ntp.org144.76.43.40
    DEgwyn.kn-bremen.de148.251.8.79
    DEhera.limescope.net188.40.128.210
    DEntp.dianacht.de77.37.6.59
    DEntp.rueckgr.at78.47.148.174
    DEntp1.madavi.de81.169.169.173
    DEntp1.theremailer.net85.10.240.253
    DEntp2.madavi.de85.214.229.39
    DEntp3.madavi.de85.214.240.94
    DEstratum2-3.NTP.TechFak.Uni-Bielefeld.de129.70.132.32
    DEstratum2-3.NTP.TechFak.Uni-Bielefeld.de129.70.132.32
    DEstratum2-4.NTP.TechFak.Uni-Bielefeld.de129.70.132.33
    DEtime.edv-froehlich.de84.201.32.108
    DEtime2.one4vision.de212.82.32.26
    DEzeus.limescope.net88.198.230.196
    DKdk.pool.ntp.org77.243.43.213
    DKntp.dvconsulting.dk195.234.155.123
    DKntp.gal.dk195.234.155.124
    EEee.pool.ntp.org212.7.1.131
    ESes.pool.ntp.org158.227.98.15
    EShora.oxixares.com37.187.170.220
    Europeeurope.pool.ntp.org88.178.32.159
    FIfi.pool.ntp.org194.100.206.70
    FIntp.lekksi.com81.22.251.67
    FItick.keso.fi82.197.0.130
    FItock.keso.fi82.197.0.130
    FRfr.pool.ntp.org151.80.124.104
    FRntp.crifo.org195.154.176.80
    FRntp.demongeot.biz46.105.237.136
    FRntp.home-dn.net62.210.109.229
    FRntp.obspm.fr145.238.203.10
    FRntp.via.ecp.fr138.195.130.62
    FR Lyonntp.univ-lyon1.fr134.214.100.6
    GRgr.pool.ntp.org194.177.210.54
    GRntp.mfa.gr195.167.30.249
    HKhk.pool.ntp.org218.189.210.3
    HRhr.pool.ntp.org161.53.131.133
    HRos.ntp.carnet.hr161.53.30.104
    HRri.ntp.carnet.hr161.53.30.170
    HRst.ntp.carnet.hr161.53.30.50
    HRzg1.ntp.carnet.hr161.53.123.5
    HRzg2.ntp.carnet.hr161.53.160.5
    HUhu.pool.ntp.org195.228.75.149
    HUntp.mandrivalinux.hu213.157.100.100
    HUtime.kfki.hu148.6.0.1
    IDid.pool.ntp.org114.141.48.158
    IEie.pool.ntp.org54.194.18.100
    IEntp.maths.tcd.ie134.226.81.3
    IE Dublinsalmon.maths.tcd.ie134.226.81.11
    ILil.pool.ntp.org109.226.40.40
    INin.pool.ntp.org125.62.193.121
    IRir.pool.ntp.org194.225.150.25
    ITit.pool.ntp.org212.45.144.206
    ITntp.prato.linux.it62.48.53.90
    ITquassia.associazione-tp.it212.45.144.11
    JPjp.pool.ntp.org129.250.35.251
    KRkr.pool.ntp.org114.70.64.65
    LKlk.pool.ntp.org192.248.1.162
    LTlt.pool.ntp.org212.59.0.2
    LUlu.pool.ntp.org80.92.86.23
    LVlv.pool.ntp.org178.16.23.50
    MDmd.pool.ntp.org178.168.120.183
    MDntp.fedoramd.org178.168.120.183
    MDntp2.idsi.md193.226.65.2
    MGmg.pool.ntp.org41.188.33.6
    MKmk.pool.ntp.org79.99.56.72
    MXmx.pool.ntp.org192.36.143.130
    MYmy.pool.ntp.org202.45.138.123
    NCnc.pool.ntp.org115.126.160.4
    NLnl.pool.ntp.org91.148.192.49
    NLntp.edge.tillo.ch31.3.135.236
    NLntp.minian.org83.96.227.85
    NLntp.wsrs.net5.200.6.34
    NOno.pool.ntp.org31.185.27.200
    NOntp-public.uit.no129.242.4.241
    NZntp.iprolink.co.nz203.152.107.68
    NZntp.massey.ac.nz130.123.108.7
    NZntp.public.otago.ac.nz139.80.64.114
    NZnz.pool.ntp.org103.242.68.68
    NZtk3.ihug.co.nz203.109.129.1
    North America0.north-america.pool.ntp.org132.163.4.101
    North America1.north-america.pool.ntp.org198.211.106.151
    North America2.north-america.pool.ntp.org104.236.155.134
    North America3.north-america.pool.ntp.org132.163.4.102
    OMom.pool.ntp.org85.154.240.78
    Oceaniaoceania.pool.ntp.org103.242.70.4
    PApa.pool.ntp.org64.116.170.5
    PKpk.pool.ntp.org103.44.223.15
    PLntp2.net.icm.edu.pl213.135.59.38
    PLntp2.radioalfa.pl89.174.70.2
    PLpl.pool.ntp.org178.33.50.131
    PTntp04.oal.ul.pt194.117.9.136
    PTpt.pool.ntp.org5.135.59.152
    ROntp1.dooh.ro89.36.93.9
    ROntp2.dooh.ro89.36.93.9
    ROro.pool.ntp.org78.96.7.8
    RSrs.pool.ntp.org147.91.26.20
    RUntp.letinet.ru95.140.94.2
    RUntp.psn.ru194.149.67.129
    RUntp1.kangran.su46.252.169.154
    RUntp2.kangran.su89.221.207.113
    RUru.pool.ntp.org31.131.249.26
    RUticktock.net.ru80.93.53.29
    SEntp.systemtid.se212.181.208.227
    SEse.pool.ntp.org192.36.143.153
    SEtime.flygplats.net185.2.154.76
    SGsg.pool.ntp.org218.186.3.37
    SIntp1.arnes.si193.2.1.117
    SIntp2.arnes.si193.2.1.92
    SIsi.pool.ntp.org93.103.22.152
    SKsk.pool.ntp.org62.168.65.36
    SVclock.cimat.ues.edu.sv138.255.153.68
    SVsv.pool.ntp.org168.243.227.194
    South Americasouth-america.pool.ntp.org146.164.48.5
    South Australiantp.adelaide.edu.au129.127.40.3
    THth.pool.ntp.org122.155.169.213
    TRntp1.sibernet.com.tr95.9.114.16
    TRntp1.sibernet.com.tr95.9.114.16
    TRtr.pool.ntp.org78.46.53.11
    TWtw.pool.ntp.org103.226.213.30
    TZtz.pool.ntp.org41.222.88.32
    UAntp.vc.ukrtel.net213.179.228.16
    UAua.pool.ntp.org91.236.251.24
    UKextntp0.inf.ed.ac.uk129.215.160.240
    UKextntp1.inf.ed.ac.uk129.215.42.240
    UKntp.cis.strath.ac.uk130.159.196.117
    UKntp.exnet.com79.135.97.70
    UKntp.markyate.net84.45.170.220
    UKntp.pinklemon.net109.74.206.120
    UKntp1.uk.uu.net158.43.128.66
    UKtick.myodn.ch109.74.202.157
    UKuk.pool.ntp.org46.101.81.119
    UK Manchesterntp2a.mcc.ac.uk130.88.202.49
    UK Manchesterntp2b.mcc.ac.uk130.88.200.4
    UK Manchesterntp2c.mcc.ac.uk130.88.200.6
    UK Manchesterntp2d.mcc.ac.uk130.88.212.143
    UK Scotland Glasgowntp.cs.strath.ac.uk130.159.196.118
    USac-ntp0.net.cmu.edu128.2.1.20
    USac-ntp1.net.cmu.edu128.2.1.21
    USac-ntp2.net.cmu.edu128.2.1.22
    USmorose.quex.org206.222.28.90
    USntp.myfloridacity.us71.40.128.146
    USntp.rfnj.org74.63.215.214
    USntp1.chrisjohnston.org50.56.172.94
    USntp1.sjbcom.com65.216.242.42
    USntp1.stsn.net72.254.0.254
    USntp2.chrisjohnston.org50.56.172.94
    USntp3.stsn.net72.255.0.254
    USntp5.tamu.edu128.194.254.9
    USntppub.tamu.edu128.194.254.9
    USsaman-gh.co.uk146.185.168.168
    USthecraag.com96.238.93.48
    UStime.cachenetworks.com69.31.3.3
    UStime.nist.gov216.229.0.179
    USus.pool.ntp.org168.158.178.5
    US AZdecimal.lib.ci.phoenix.az.us148.167.132.201
    US AZdewey.lib.ci.phoenix.az.us148.167.132.200
    US AZntp3.linocomm.net89.188.26.129
    US CAntp.drydog.com216.218.196.162
    US CAntp.nblug.org208.201.242.2
    US CAntp.ucsd.edu132.239.1.6
    US CAntp1.sf-bay.org204.26.59.157
    US CAreva.ziaspace.com206.221.211.41
    US COntp1.linuxmedialabs.com96.47.0.50
    US Carson City, Michigannisttime.carsoncity.k12.mi.us198.111.152.100
    US GArolex.usg.edu198.72.72.10
    US ILntp.mya.org75.150.206.145
    US ILstratum2.ord2.publicntp.net50.31.2.213
    US IL Urbana-Champaignntp-0.cso.uiuc.edu130.126.24.53
    US IL Urbana-Champaignntp-1.cso.uiuc.edu130.126.24.24
    US IL Urbana-Champaignntp-2.cso.uiuc.edu130.126.24.44
    US KSntp1.kansas.net64.6.144.6
    US KSntp2.kansas.net158.247.20.1
    US LDSBC, Salt Lake City, Utahntp-nist.ldsbc.net198.60.73.8
    US La Grande, Oregonnist-time-server.eoni.com216.228.192.69
    US MAtimelord.w1nr.net173.255.227.205
    US MNns.nts.umn.edu128.101.101.101
    US MNnss.nts.umn.edu134.84.84.84
    US MNntp157.sntp.us63.228.0.157
    US MOtime-ext.missouri.edu128.206.12.130
    US MTchronos1.umt.edu192.73.48.1
    US MTchronos2.umt.edu192.73.48.2
    US MTchronos3.umt.edu192.73.48.6
    US Macon, Georgianist1-macon.macon.ga.us98.175.203.200
    US NCclock1.unc.edu152.2.21.1
    US NIST, Gaithersburg, Marylandtime-a.nist.gov129.6.15.28
    US NIST, Gaithersburg, Marylandtime-c.nist.gov129.6.15.30
    US NJtick.jrc.us208.90.144.52
    US NJtock.jrc.us208.90.144.53
    US NVcuckoo.nevada.edu131.216.1.101
    US NVtick.cs.unlv.edu131.216.22.24
    US NV Las Vegastock.cs.unlv.edu131.216.22.26
    US NYntp.pbx.org66.250.45.2
    US NYntp0.cornell.edu132.236.56.250
    US NYsundial.columbia.edu128.59.59.177
    US NY New Yorkntp.ctr.columbia.edu128.59.64.59
    US NY New Yorktimex.cs.columbia.edu128.59.16.20
    US PAfuzz.psc.edu128.182.58.100
    US PA University Parkclock.psu.edu128.118.25.3
    US Southfield, Michigannist.netservicesgroup.com64.113.32.5
    US TXntp.bytestacker.com173.255.196.241
    US TXntp.fwwds.com69.164.201.165
    US TXntp.jentfoo.com173.203.211.73
    US TXntp.tmc.edu128.249.1.10
    US TXntp1.jtsage.com72.14.183.239
    US TXsundial.cis.sac.accd.edu209.184.112.198
    US TXtick.jpunix.net188.226.158.42
    US TXtick.mattnordhoff.com67.18.187.111
    US TXticker.cis.sac.accd.edu209.184.112.199
    US TXtime.xenscale.com72.14.188.195
    US University of Colorado, Boulderutcnist.colorado.edu128.138.140.44
    US VAntp-1.vt.edu198.82.247.51
    US VAntp-2.vt.edu198.82.247.71
    US VAntp-3.vt.edu198.82.247.108
    US VAntp-4.vt.edu198.82.247.131
    US VA Blacksburgvtserf.cc.vt.edu198.82.162.213
    US WAtick.mtnlion.com204.13.164.164
    US WIntp1.netwrx1.com108.76.168.145
    US WIntp3.sf-bay.org206.55.70.42
    US WI Madisonntp1.cs.wisc.edu128.105.39.11
    US WI Madisonntp2.cs.wisc.edu128.105.38.11
    US WI Madisonntp3.cs.wisc.edu128.105.37.11
    VEve.pool.ntp.org190.202.98.221
    VNvn.pool.ntp.org220.231.122.99
    YUyu.pool.ntp.org212.200.82.130
    ZAza.pool.ntp.org146.231.129.86
    worldwidepool.ntp.org107.170.242.27
    Last revised/verified: 2010-03-15
  4. java.lang.System.currentTimeMillis () will give you the time in milliseconds since 1970 Jan 1 0:00 GMT (Greenwich Mean Time). This is your best bet for computing elapsed times. Freshly minted  java.util.Dateutil.Date objects contain the current GMT date/time stamp as do freshly minted java.util. GregorianCalendar objects.
  5. Time.gov is a government website that will give you local time.
  6. XP, W2003, Vista, W2008, W7-32, W7-64, W8-32, W8-64, W2012, W10-32 and W10-64 will consult a Microsoft web clock if you issue the command w32tm.exe /resync or right click the time display in the bottom right and select adjust date and time ⇒ Internet time. If time.windows.com time source is not reliable, (the usual case) you can configure the timeserver to a different one, perhaps from pool.ntp.org, e.g. us.pool.ntp.org, 0.ca.pool.ntp.orgw32tm.exe will only work after the W32Time service is started in the Windows task manager. Not that W32tm uses the stripped down SNTP (Simple Network Time Protocol) protocol, not the more accurate NTP.

    rem Using w32tm.exe to resync the Windows clock with SNTP
    rem This must be run as administrator.
    rem Start the service (need be done only once per boot)
    sc.exe start W32Time >nul:
    rem probe an NTP clock on the net with SNTP
    w32tm.exe /resync >nul:
    rem -30-

    In W10-32 and W10-64 w32tm.exe will not work unless you run as administrator. You can do it by starting a command window with run as administor then running the bat file containing the w32tm.exe call.

  7. pool.ntp.org maintains a set of servers all over the world. You can find one just by prefixing your 2-letter country code e.g ch.pool.ntp.org for Switzerland or 0.ca.pool.ntp.org for Canada or us.pool.ntp.org for the USA. The W32Time service must be running for W32tm.exe to work. You can start it from the command line with sc.exe start W32Time.
  8. Installing Meinberg NTP software for Windows is very easy to set up. It does not require run as administer. It is very accurate.
  9. atomic wall clock From the NIST (National Institute of Standards and Technology) WWVB radio signal broadcast from Fort Collins, Colorado. This is how high tech wall clocks and wrist watches maintain perfect time and know when to flip back and forth to daylight savings. They are called analog atomic clocks and digital atomic clocks, though there is nothing radioactive in them. They are merely radio-synchronised from a government atomic clock.
    radio-synced clocks for more details and information on where to buy them
  10. From a signal PBS embeds in its TV broadcasts. This is how VCRs (Videocassette Recorders) can get the time automatically.
  11. From the CBC (Canadian Broadcasting Corporation) radio time signal each day at 10 AM on the FM broadcast stations.
  12. From a signal broadcast on the AC (Alternating Current) power, put here by the utility company.
  13. From your TV Station broadcast channel guide.
Make sure you use secondary Stratum 2 servers only. Primary stratum 1 are reserved for synching stratum 2 clocks.

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