Configuring Windows 2003 to Run as a Ntp Network Time Server

Time synchronisation in modern computer networks is essential, all computers need to know the time as many applications, from sending an email to storing information are reliant on the PC knowing when the event took place.

Microsoft Windows Server from 2000 onwards has a time synchronisation utility built into the operating system called Windows Time (w32time.exe) which can be configured to operate as a network time server.

Windows 2003 Server can easily set the system clock to use UTC (Coordinated Universal Time, the World’s time standard) by accessing an Internet source (either: time.windows.com or time.nist.gov). To achieve this, a user merely has to double click the clock on their desktop and adjust the settings in the Internet Time tab.

It must be noted however, that Microsoft and other operating system manufacturers strongly advise that external timing references should be used as Internet sources can’t be authenticated.

To configure the Windows Time service to use an external time source, click Start, Run and type regedit then click OK.

Locate the following subkey:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersType
In the right pane, right-click Type then click Modify, in edit Value type NTP in the Value data box then click OK.

Locate the following subkey:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeConfigAnnounceFlags.

In the right pane, right-click AnnounceFlags and click Modify. The ‘AnnounceFlags’ registry entry indicates whether the server is a trusted time reference, 5 indicates a trusted source so in the Edit DWORD Value box, under Value Data, type 5, then click OK.

Network Time Protocol (NTP) is an Internet protocol used for the transfer of accurate time, providing time information along so that a precise time can be obtained
To enable the Network Time Protocol; NTPserver, locate and click:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpServer
In the right pane, right-click Enabled, then click Modify.

In the Edit DWord Value box, type 1 under Value data, then click OK.

Now go back and click on
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersNtpServer

In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type the Domain Name System (DNS), each DNS must be unique and you must append 0×1 to the end of each DNS name otherwise changes will not take effect.

Now click Ok.

Locate and click the following
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpClientSpecialPollInterval
In the right pane, right-click SpecialPollInterval, then click Modify.

In the Edit DWORD Value box, under Value Data, type the number of seconds you want for each poll, ie 900 will poll every 15 minutes, then click OK.
To configure the time correction settings, locate:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Timeconfig

In the right pane, right-click MaxPosPhaseCorrection, then Modify, in the Edit DWORD Value box, under Base, click Decimal, under Value Data, type a time in seconds such as 3600 (an hour) then click OK.
Now go back and click:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Timeconfig
In the right pane, right-click MaxNegPhaseCorrection, then Modify.

In the Edit DWORD box under base, click Decimal, under value data type the time in seconds you want to poll such as 3600 (polls in one hour)
Exit Registry Editor

Now, to restart windows time service, click Start, Run (or alternatively use the command prompt facility) and type:

net stop w32time && net start w32time
And that’s it your time server should be now up and running.

Windows Time Server: Synchronising Your Network With Ntp

Nearly all a computers activity involves time whether logging a timestamp for when a network was accessed to sending an email, knowing the time is crucial for computer applications.

All computers have an on-board clock that provides time and date information. These Real Time Clock (RTC) chips are battery backed so that even when off they can maintain time, however these RTC chips are mass produced and cannot maintain accurate time and tend to drift.

For many applications this can be quite adequate, however if a computer is on a network and needs to talk to other machines, failing to be synchonised to the correct time can mean many time-sensitive transactions can not be completed and can even leave the network open to security threats.

All versions of Windows Server since 2000 have included a time synchronization facility, called Windows Time Service (w32time.exe), built into the operating system. This can be configured to operate as a network time server synchronizing all machines to a specific time source.

Windows Time Service uses a version of NTP (Network Time Protocol), normally a simplified version, of the Internet protocol which is designed to synchronise machines on a network, NTP is also the standard for which most computer networks across the global use to synchronise with.

Choosing the correct time source is vitally important. Most networks are synchronized to UTC (Coordinated Universal Time) source. UTC is a global standardized time based on atomic clocks which are the most accurate time sources.

UTC can be obtained over the Internet from such places as time.nist.gov (us Naval Observatory) or time.windows.com (Microsoft) but it must be noted that internet time sources can not be authenticated which can leave a system open to abuse and Microsoft and others advise using an external hardware source as a reference clock such as a specialized NTP server.

NTP servers receive their time source from either a specialist radio transmission from national physics laboratories which broadcast UTC time taken from an atomic clock source or by the GPS network which also relays UTC as a consequence of needing it to pin point locations.

NTP can maintain time over the public Internet to within 1/100th of a second (10 milliseconds) and can perform even better over LANs.

To configure Windows Time Service to use an external time source simply follow these instructions.

Locate the registry subkey.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParameters

Right click type then Modify the Value by inserting NTP in the Value Data box.

Right click ReliableTimeSource, then Modify the Edit DWORD Value box, by inserting 0 (zero).

Right-click NtpServer then Modify the Edit Value by typing the Domain Name System (DNS), (note each DNS must be unique).

Now locate the original subkey and right-click Period Modify the Edit DWORD Value box with the poll interval (how often a NTP server polls the time), under Value Data (recommended 24)

Run the following command line, Net stop w32time && net start w32time.

Now enable NTP by locating the subkey, HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpServer

Right click Enabled and modify the Value data box by typing 1.

Right Click SpecialPollInterval in the right pain of the subkey HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpClientSpecialPollInterval. Edit the DWORD value box the time you want for each poll (900 will poll every 15 minutes)

Locate HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Timeconfig

To configure the time correction settings right click MaxPosPhaseCorrection, then modify the DWORD Value box with a time in seconds such (select decimal under base first, 3600 = one hour)

Now do the same for MaxNegPhaseCorrection the restart windows time service by running (or alternatively use the command prompt facility) net stop w32time && net start w32time.

To synchronise each machine simply type W32tm/ -s in the command prompt and the time server should now be working correctly (note it may take several polls before the correct time is displayed).

 

 

 

 

 

 

 

 

 

How to Configure a Windows Time Server

The latest Microsoft Windows operating systems have a time synchronisation utility installed by default called ‘Windows Time’. The Windows time service allows a Microsoft network to provide time synchronisation of machines in a domain. This article introduces how to configure the Microsoft Windows 2000 and 2003 operating systems to operate as a SNTPNTP Time Server. The article discusses how to change Windows registry entries to configure the Time Service.

Before modifying any Windows registry settings, it is a good idea to save the registry. In the even of any difficulties, the registry can be restored to its former state.

Windows 2000 Time Service

Windows 2000 has an integrated network time synchronization service, installed by default, which can be configured to synchronize to a Time Server. In fact, by changing associated registry settings, the service can act as both a time client and a time server to synchronize other network time clients.

The Windows Time service should be present in the systems service list. The application executable is ‘w32time.exe’. The parameter list for time service should be present in the in the registry at:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParameters

The Windows 2000 operating system can operate as a time client and synchronise to a time server by setting the parameter ‘NTP Server’ to the IP address of a Time Server.

By default, the Windows 2000 machine will synchronize to the specified time server every 8 hours, or 3 times a day. This may not be enough to maintain accurate synchronization and can be easily increased. Setting the ‘Period’ parameter to how many times each day synchronisation is required can reduce the period. Setting the ‘Period’ parameter to 48 will activate synchronization with the time server once every half hour.

The Windows 2000 operating system can also be configured to act as a time server by setting the ‘Local NTP’ registry setting to ’1′.

After changing any of the registry settings for the windows time service, the service must be restarted for the settings to take effect. The time service can be started or stopped from the service control applet in the Administrative Tools menu. The service can also be controlled via the DOS net command thus:

‘net start w32time’ and ‘net stop w32time’

Windows 2003 Time Service

With Windows 2003, Microsoft has expanded on the original Windows 2000 SNTP time service by providing a true NTP implementation. The Windows 2003 time service, installed by default, can synchronise to a NTP Server. Indeed, by changing registry settings, the time service can act as both a time server and client to synchronize other time clients in the domain.

The ‘Windows Time’ service should be present in the systems service list. The application executable is ‘w32time.exe’. The parameter list for the Windows 2003 time service should be present in the registry at:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Time

To configure the Windows 2003 operating system to synchronize to an external time server, edit the following registry entries:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersType

Set the ‘Type’ registry entry to ‘NTP’, which specifies synchronization to a NTP time server.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNTPClientSpecialPollInterval

The ‘Special Poll Interval’ registry entry defines the period in seconds that the Windows 2003 operating system should poll the time server. A recommended value is 900, which equates to a polling period of every 15 minutes.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeConfigAnnounceFlags

Set the ‘Announce Flags’ registry entry to 5 indicating a reliable time reference.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNTPServerEnabled

Changing the ‘Enabled’ flag to the value 1 enables the NTP Time Server.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersNtpServer

The ‘NTP Server’ parameter is used to provide a list of DNS names or IP addresses, separated by a space, of time servers that the Windows 2003 operating system can synchronize to.

Troubleshooting the Time Service

A number of isuues may be encountered when configuring the Microsoft Windows Time Service. SNTP and NTP operates using the UDP protocol over TCP/IP. Therefore, the TCP/IP network protocol must be active for SNTPNTP to operate. Synchronisation issues may also arise when SNTPNTP attempts to synchronise to an inaccurate time server reference or if network delays are excessive.

Synchronising Network Device and Components

In addition to synchronizing Microsoft Windows servers and workstations, time servers can also be used to synchronise network devices, such as switches, routers and hubs. Any network infrastructure that can synchronise to a NTP or SNTP time server can be pointed to the Windows time server to obtain synchronisation. In this way the whole network and accompanying infrastructure can be accurately synchronised to a time reference.

Experiencing First Time Web Hosting

After purchasing a domain name next step is to fill it up with contents but is it enough? No! Not yet next is –

HOSTING.

One should have proper knowledge of hosting for running his/her site successfully and its quite easy to know about it just what is required is to type ‘web hosting‘ in Google, clicking ‘I’m filling lucky’ and then simply clicking the big ‘BUY’ button on a website that appears.

Ok! That was just a joke now coming to point given below is the list of what one need to learn before choosing a web hosting company.

Disk Space

It totally depends upon the size of the website. It’s easy to calculate the volume of the disk space. It can be calculated by checking the website’s weight at one’s computer folder. But one must take care to keep some space as spare to be used in future if required.

Example, if one’s web site needs 100 MB of disk space, and then he/she must opt for the plan, which offers at least 150 MB of web space, which will help in preventing a large unexpected bill at the end of the month. This is so because most of the web hosts charge heavily afterwards for extra space.

Bandwidth

For bandwidth also earlier calculation is needed. One must try to estimate how much bandwidth (data transfer) is required for his/her web site and thereafter should get bandwidth little bit in spare.

Example, if one’s website uses 5GB bandwidth monthly, then he/she must select a plan, which offers at least 8 GB bandwidth per month. This again as in above case will help in preventing extra bill afterwards for extra bandwidth at the end of the month.

Website Speed

Website speed is an important factor while considering a hosting service as only this facility will decide how fast one’s website loads when some one visits his/her site. One must keep in mind that no visitor in future will waste his/her time by just watching website getting opened.

One must ask his/her hosting provider to provide with a list of their client’s websites to check their speed. Only after getting positive report one should move ahead.

Mail Server

Finally one must make sure that he/she gets enough email addresses with own domain name. It is not required to pay more for use of a mail server as many hosts offer this service now for free, within the hosting plan.

Thus the above points can serve a lot for a beginner and will help him/her in overcoming several problems, which can arise afterwards.

Windows 2003 Installing and Configuring an Authoritative Ntp Network Time Server

Precision and time synchronisation is highly important for modern computer networks, without synchronisation many time sensitive transactions would be impossible to carry out.

The internal clock in computers does keep time and date information but these Real Time Chips are not designed to keep perfect time as computers are mass produced and optimized for low cost rather than being perfect clocks.

Of course for a lot of applications this can be more than adequate but for time-sensitive transactions such as online purchasing not having a network that is synchronised can cause errors in transactions and can even leave the network vulnerable to fraud.

Fortunately Windows Server from 2000 onwards has a time synchronisation utility built in call windows time (w32time.exe) this can be configured to allow the machine to be used as time server.

Windows time uses a form of NTP (Network Time Protocol) which was developed over 20 years ago. It uses an algorithm to synchronise time on a network. NTP (version 4) can maintain time over the public Internet to within 10 milliseconds (1/100th of a second) and can perform even better over LANs with accuracies of 200 microseconds (1/5000th of a second) under ideal conditions.

NTP uses a single time reference and synchronises all machines on the network to that time. It can be configured to both synchronise a network using the internal clock or an external time source.

Note: Microsoft strongly recommends that you configure a time server with a hardware source rather than from the internet where there is no authentication.

To configure the Windows Time service to use an external time source, click Start, Run and type regedit then click OK.

Locate the subkey:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParameters

Right-click Type then Modify, in edit Value type NTP in the Value data box then OK.

Right click ReliableTimeSource, then click Modify.

In the Edit DWORD Value box, under Value Data, type 0, then click OK.

Right-click NtpServer in the right pane then click Modify.

In Edit Value, type the Domain Name System (DNS), each DNS must be unique.

Now click Ok.

To set the poll intervals locate:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParameters

In the right pane, right-click Period, then click Modify.

In the Edit DWORD Value box, under Value Data, type 24 then OK

Exit Registry Editor

Click Start, then Run then type the following and press Enter:

Net stop w32time && net start w32time

Network Time Protocol (NTP) is an Internet protocol used for the transfer of accurate time, providing time information along so that a precise time can be obtained

To enable the Network Time Protocol; NTPserver, locate and click:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpServer

In the right pane, right-click Enabled, then click Modify.

In the Edit DWord Value box, type 1 under Value data, then click OK.

Now go back and click on

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersNtpServer

In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type the Domain Name System (DNS), each DNS must be unique and you must append 0×1 to the end of each DNS name otherwise changes will not take effect.

Now click Ok.

Locate and click the following

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpClientSpecialPollInterval

In the right pane, right-click SpecialPollInterval, then click Modify.

In the Edit DWORD Value box, under Value Data, type the number of seconds you want for each poll, ie 900 will poll every 15 minutes, then click OK.

To configure the time correction settings, locate:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Timeconfig

In the right pane, right-click MaxPosPhaseCorrection, then Modify, in the Edit DWORD Value box, under Base, click Decimal, under Value Data, type a time in seconds such as 3600 (an hour) then click OK.

Now go back and click:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Timeconfig

In the right pane, right-click MaxNegPhaseCorrection, then Modify.

In the Edit DWORD box under base, click Decimal, under value data type the time in seconds you want to poll such as 3600 (polls in one hour)

Exit Registry Editor

Now to restart windows time service, click Start, Run (or alternatively use the command prompt facility) and type:

net stop w32time && net start w32time

And on each computer, other than the time server, type:

W32tm/ -s and the time server should be up and running

 

 

The Power of Windows Hosting – Save Time and Money

Back in 1997 when the majority of web sites were being served from UNIX servers I chose to use Windows servers. I chose Windows servers because they gave the fastest server side development environment with ASP and Access databases. I could cut my teeth on server side programming without killing my brain trying to learn Perl and CGI.

I am an entrepreneur. I don’t care much for technology for technologies sake. I care about technology for what it can do for us as humans. Business is where we can bring about products and services that we can all gain value from and improve our lives.

Windows servers allowed me to focus less on the technical aspects and focus more on the business rules, functions and features of the products and services I wanted to deliver. At that time my sites were simple directories for real estate, motor cars and local sites. Over the following 2 years I got more excited about the Windows platform as a means for more and more people like me to bring about innovations to the internet – fast.

Windows continues to be a great platform to develop dynamic, interactive, database driven sites with ASP, ASP.Net with Access or SQL Server database back ends. This is a wonderful platform to learn the basics of what it takes to develop such a site. ASP and Access provide a solid environment for anyone to learn the basics of coding and databases. The work produced with ASP and Access can be easily converted to ASP.Net and SQL Server to be far more scalable (handle more people using the site at one time).

ASP is a server side programming language based on Basic. Basic is a beginners programming language. Access is a simple desktop database application available with Microsoft Office that provides many wizards and tools to quickly develop a functional database. You will find many learning resources, tutorials and free code and samples for both ASP and Access across the internet.

Once you have developed or copied and pasted some code and server side databases together you will gain an incredible amount of confidence. You will naturally move on to more advanced projects. You will also be open to a whole new world of freely downloadable web applications (open source and generally free) to modify and try on your sites. In doing this you will come across sites written in PHP and ASP.net requiring MySQL or SQL server databases. If you are running your sites on a Windows server you can plat around with the whole world of server side scripting languages: from ASP to PHP, ASP.Net and even Perl!

The Windows Server hosting environment will help a beginner gain confidence and skills in the basics of developing a dynamic web application. Then it will allow you to progress to more advanced web applications using a mix of ASP, ASP.Net, PHP with MySQL and SQL server back-end. A good Windows host will allow you to run ASP, ASP.net and PHP with MySQL or SQL server all on the one site. You will find a Windows hosting account will give you far more freedom and flexibility to run a wide range of web applications and allow you to get a dynamic web site up and running fast.

Today I still prefer to prototype a site with ASP and then once proven move it to ASP.Net or PHP so it is scalable. ASP allows me to quickly get my ideas up and running fast. With feedback and if it is successful I can invest more time in a more appropriate language for the application with ASP.Net or PHP. A Windows hosting environment provides me this flexibility.

If you’re looking to start in the world of developing web sites or want to take your web design skills to the next level, the world of Windows hosting is a good place to start. It will allow you to develop your skills with a very simple coding language and database with ASP and MS-Access. The Windows hosting environment will feel familiar with concepts you are used to, from using the Windows operating system on your desktop or notebook. And when you’re ready to take your projects further with ASP.Net or PHP your Windows server will be able to handle that too.

In a world where time is money and both are in short supply, flexibility is key. A Windows hosting environment will provide you with the necessary flexibility to save both time and money and get your web projects up and running faster.

Keeping Accurate Time on Your Computer Using Ntp Servers

PC’s are notoriously poor at keeping time. I am sure the you have probably noticed the time on your PC drifts away from the correct time by a number of seconds or even minutes each day. This is because real-time clock chips, used in modern PC’s, use similar components to every-day clocks and watches and are just as prone to drift away from the correct time. However, there are things that you can do to maintain accurate time on your PC. This article discusses ways in which you can maintain continuously accurate system time on your computer system. It looks at how Internet time references and NTP servers can be utilised for computer time synchronisation.

There are a large number of Internet based time references that use the Network Time Protocol (NTP) to synchronise time clients. NTP was developed over twenty-five years ago at the University of Delaware by Dr D. Mills, it remains one of the oldest protocols in constant use. The protocol was developed to provide accurate synchronisation of time between time servers and clients. Internet based NTP servers synchronise their time to accurate external reference clocks, such as GPS, national radio time standards or precise atomic clocks. Accurate time is then passed from the NTP server to network clients for synchronisation.

Most present day computer operating systems have the ability to synchronise time with an accurate internet based NTP server. Linux, Unix, Microsoft Windows XP/2000/2003/Vista and Novell all have routines for NTP time synchronisation. Generally, client-side configuration consists of providing the client with the domain name of the NTP server.

Windows XP/2000/2003/Vista machines can accept the IP address/domain name of a NTP server in the time properties/internet time tab. Periodically, the NTP server will be contacted to obtain time and perform synchronisation.

The Linux and Unix operating systems have a NTP daemon available from the NTP web site at ‘ntp.org’. The NTP daemon can be configured to otain time from other NTP servers or act as a server in its own right. The ‘ntp.conf’ configuration file contains a list of servers that can be contacted. Simply enter the IP address or domain name of a NTP server in the list.

To maintain accurate time on a computer system using NTP is very straightforward. However, there are many other more advanced features of the NTP protocol. There are a number of security features that allow service ristrictions and server authentication. Additionally, there are numerous reference clock drivers available to synchronise NTP with a precise external reference – providing a full-blown NTP server installation.

To conclude, computer systems provide notoriously poor time keeping hardware. Without help, standard time keeping devices are just not up to the task of providing system-wide time synchronisation. The solution is to use the NTP protocol and get your computers synchronised to some of the most accurate clocks in the world.

Ntp Server Systems ? the Network Time Protocol

The Network Time Protocol (NTP) is utilised by NTP Server systems to distribute accurate time information to network time clients. The NTP protocol is widely used throughout the Internet to provide synchronisation of computers and processes. This article discusses how NTP server systems utilise the Network Time Protocol to provide networks with an accurate reference of time.

NTP Overview

NTP has been in use as an Internet protocol for over 25 years. It is the longest running continuously operating Internet protocol. The protocol was born through the need to provide synchronisation of time critical processes across the Internet. NTP primarily runs on LINUX and UNIX platforms including Free-BSD but has also been, in part, ported to Windows operating systems. Dedicated NTP server systems generally utilise the LINUX operating system.

The NTP Protocol

NTP is designed to provide network time clients with three products: system clock offset, round-trip delay and dispersion relative to a specified reference clock. Clock offset is the time difference between the local clock and reference clock. Round-trip delay measures the amount of time the protocol takes to receive a response from the server. Dispersion is the maximum error of the local clock relative to the specified reference.

NTP Stratum

NTP operates in a hierarchical manner, the primary reference followed by secondary references and clients. At the top of the hierarchy, the primary reference is usually synchronised to an external time source such as a radio or GPS clock. The primary reference is attributed a stratum of one. Each level down in the hierarchy is attributed a stratum one greater than the preceding level. As the stratum increases, the accuracy of the reference degrades slightly due to inconsistencies in network path timing. Secondary references have a stratum of between two and fifteen.

NTP Messages

NTP utilises the UDP (User Data-gram Protocol) protocol. The NTP message consists of a number of fields: Leap Indicator; Version Number; Mode; Stratum; Poll; Precision; Root Delay; Root Dispersion; Reference Identifier; Reference Timestamp; Originate Timestamp; Receive Timestamp; Transmit Timestamp; Key Identifier and Message Digest.

The leap indicator warns of an impending leap second addition or deletion. The version number indicates the NTP version in use. Mode specified the NTP mode of the current message. Stratum is an eight-bit value indicating the hierarchical level of the reference clock. Poll interval specifies the maximum interval between messages. Precision specifies the accuracy of the local clock. Root delay indicates the round-trip delay time to the reference. Root dispersion indicates the nominal error relative to the primary reference. Reference identifier is a 4-character ASCII string identifying the reference source, such as GPS, DCF or MSF. Reference timestamp specifies the time at which the reference clock was last corrected. The Originate Timestamp specifies the time the NTP request message departed the client for the NTP server. Receive timestamp specifies the time the NTP request message was received by the NTP server. Transmit timestamp specifies the time the NTP response message was transmitted by the server to the client. The key identifier field is utilised when authentication is required and provides the message authentication code.

NTP Server Operation

A NTP server can operate in three modes: unicast; anycast and multicast. In unicast and anycast modes, the client transmits a NTP request message to the server. The server responds with a NTP time message that the client uses for time synchronisation. In multicast mode, NTP time messages are broadcast at periodic specified intervals.

NTP Reference Clocks

Primary NTP servers can synchronise with a number of external reference time sources. The GPS (Global Positioning System) is often used to provide an accurate timing reference. There is also a number of national time and frequency radio broadcasts available. The WWVB radio time broadcast is transmitted from Colorado and covers most of the US. The DCF-77 radio time signal is broadcast from Frankfurt, Germany, and covers much of central and Western Europe. The MSF radio time signal is broadcast from Rugby, UK, and covers the British Isles and much of Western Europe. Other local time and frequency radio broadcasts include: TDF, France, and CHU, Canada.

NTP Versions

The current release of NTP is version 4. The only significant modification to the protocol between versions 3 and 4 is a slight header re-interpretation to accommodate IPv6.

SNTP – Simple Network Time Protocol

SNTP is a simplification of the Network Time Protocol, where the complexities of the full-blown protocol are not required. SNTP can be implemented when the high synchronisation performance of NTP is not required. The message format of the SNTP protocol is almost identical to that of the NTP protocol. However, the complex subroutines designed to maintain a highly accurate synchronised time are removed or simplified. Small computers with reduced processing power, such as micro-controllers or monitoring equipment most often use SNTP. The SNTP and NTP protocols are fully interchangeable, a SNTP client can synchronise to a NTP server without any issues.

More Information: NTP RFC’s

The original Network Time Protocol was introduced in RFC 958 (Request for Comments: 958). The full NTP version 3 protocol and synchronisation algorithms are described in RFC 1305. The SNTP version 4 protocols are described in RFC 2030.

Maintaining Precise Time on your Computer by Utilising Ntp Servers

Computer servers and workstations have integrated real-time clocks that are based on simple, cheap, crystal oscillators. The real-time clock is battery backed and maintains system time even when the computer is switched off. However, crystal oscillators characteristics change significantly with temperature variation, which can cause the time to drift by several minutes each day. This article describes how Internet or Intranet based NTP servers can be utilised to maintain accurate time on a computer system.

NTP, or Network Time Protocol, was originally developed over 25 years ago as a means of distributing accurate time around the Internet. It is one of the oldest network protocols still in use today. NTP allows network time clients to synchronise to Internet based NTP time servers. It is an integral part of the Internet network structure.

Many operating systems including Microsoft Windows, LINUX, UNIX and Novell Netware integrate the ability to synchronise their system time by utilising NTP or its reduced sister protocol SNTP (Simple Network Time Protocol). Most NTP clients only require a single, or multiple, NTP server address to be specified and will periodically synchronise with the specified NTP server.

There a large number of Internet hosted NTP servers. Most synchronise with external timing reference such as GPS or time and frequency radio broadcasts. NTP servers that synchronise to an external timing reference are designated as stratum 1 time servers, this is because they sit at the head of the network time hierarchy. NTP servers that synchronise to stratum1 time server are designated stratum 2 and so on.

Below is a list of a small number of the most popular NTP servers available across the Internet. You should choose a NTP server close to you geographic locality, so as to reduce network round trip delays.

ntp.my-inbox.co.uk – Locality: United Kingdom. time.nist.gov – Locality: United States. canon.inria.fr – Locality: France. ptbtime1.ptb.de – Locality: Germany. clock.isc.org – Locality: Canada.

Most NTP servers are based on the LINUX operating system. The NTP software distribution is a freely downloadable application supplied under the GNU public licence. NTP source code and documentation can be obtained from the ‘ntp.org’ web-site. Under LINUX, NTP runs a daemon, periodically contacting specified NTP servers and synchronising system time.

Microsoft Windows operating systems utilise Microsoft’s proprietary time synchronisation service ‘Windows Time’. The Windows Time service can be configured via registry settings to synchronise with network time servers at specified intervals.

To conclude, Internet based NTP servers are readily available free sources of precise time. Additionally, most modern operating systems have the ability to contact and synchronise with NTP servers without the need for additional software. So, provided your network has an Internet connection, there is no longer any need to continue with inaccurate system time.

Synchronise Time on Your Pc Using Ntp Servers

Clocks are essential for computers. Everything from sending and email to turning a PC on will involve a timestamp. Computers are reliant on knowing when processes happen and when they need to happen.

However, the internal clock chips on a computer, known as Real Time Chips (RTC) are mass manufactured and are optimized for economy and not accurate time keeping. As a result the clocks on computers are prone to drift.

This doesn’t cause too many problems for the home user; emails may arrive before they are sent but for day-to-day tasks perfect synchronization is not too important.

However, an inaccurate clock can leave a system open to abuse and for computers acting as servers a lack or synchronization can cause untold havoc particularly if all machines on a network are telling different times.

However accurate time on a PC is relatively straightforward to achieve as the world’s leading protocol for ensuring time synchronization, NTP (Network Time Protocol) is already installed in Windows and UNIX.

Note: some operating systems contain a simplified version of NTP (SNTP) but is is quite adequate for most time synchronisation applications, if more precise time is required then NTP (currently on version 4) is available free via ntp.org.

NTP has been developed over the last 25 years and is without doubt the best timing synchronisation protocol available (there are others on the market but 99.9 percent of time servers use NTP).

NTP is used by a computer network to synchronise to an absolute source, a timing reference from an atomic clock that relays the world time scale UTC (Coordinated Universal Time) either via the Internet or from a national time standard radio broadcast or even the GPS network.

For most modern operating systems to synchronise to an absolute UTC source over the Internet is incredibly easy with just the domain address needed to be entered. In Windows this is done by clicking the Internet time tab on the time properties box (double click the clock) for Linux and Unix the domain address can be entered in the ntp.conf file.

It must be noted however, that Microsoft and others suggest an external hardware source is used as Internet timing references can’t be authenticated, leaving a system open to abuse or a malicious attack.

There are a multitude of external time servers available the majority of which use NTP to connect to either a radio transmission (only possible if a signal from a national transmitter is obtainable) or the GPS network (though a GPS antenna).

With a GPS or radio referenced NTP time server accuracy of a few milliseconds can be achieved relatively easily.

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