Time server – Using NTP for Synchronisation

A time server is a generic term for a device that receives and distributes time.  Time servers are available across the Internet or dedicated devices can be bought that offer higher accuracy and more security.

Whilst many manufacturers produce time server devices and other synchronisation tools they all have one thing in common in that they all utilise Network Time Protocol (NTP).

Whilst NTP is not the only time synchronisation software available it is used in the vast majority of synchronisation tools with some 99% of time synchronisation being conducted using NTP. NTP is a protocol used by everyone from NASA to NASDAQ and owes much of its dominance or the time synchronisation market to the dedicated team that continue to update, upgrade and develop NTP (many of whom do not get paid).

NTP is in fact almost as old as the Internet itself having been unveiled as early as 1979. It was developed by Professor David Mills and his team from Delaware University who continue to update and develop it alongside hundreds of dedicated hobbyists referred to as the Internet timekeepers.

NTP is now on version 4 and versions of NTP are included as standard with most operating systems allowing any Windows or Linux computer to run as a time server. However, for those serious about time synchronisation or wanting to keep a network secure there is no real substitute than a dedicated time server that can distribute time sent directly from an atomic clock using NTP.

Free time server check tool

How accurate is the time you receive?

Unfortunately many Internet time servers are wholly inaccurate, however, this free and easy to use tool by Galleon Systems lets you check a server accuracy and reliability. Free to download and complete with instructions – an essential tool for anybody relying on the Internet for UTC time.

To download please visit Galleons NTP server site:

Galleon’s NTP server checker:

Time Server – Suppliers

Here is a list of links to  some of the most reputable time server manufacturers and suppliers from all over the world by country of origin.

UK
France
Germany
Italy
Spain
Poland
North America
Middle East

Time Server – FAQS

What is a time server?

A time server is a hardware device that distributes a single time source amongst a network to ensure all computers and devices are synchronised

What is NTP?

Network Time Protocol is a set of software instructions designed to distribute time across computers. NTP uses a complex algorithm to work out d inaccuracies and compensates for them by advancing or retarding the system clock.

What is UTC?

Coordinated Universal Time (UTC) is the offical global timescale. It is used by computer networks throughout the world. It is based on the time told by atomic clocks but compensates for the slowing of the Earth’s rotation by adding Leap Seconds, this also keeps it inline with GMT (Greenwich Meantime) sometimes referred to as UT1.

How does a time server receive UTC?

UTC can be received by either tuning in to a national time and frequency broadcast on long-wave administered by national physics laboratories, although not every country has one. Alternatively as GPS satellites (Global Positioning System) all carry an onboard atomic clock which transmits timing information this can be used also as a timing source for network time servers.

Can’t I use the Internet as a timing source?

You can, and there are many sources of UTC time on the Internet but very few offer any useful accuracy and for those that do the distance away can cause a drop-off in precision. More importantly, Internet time sources are exterior to your firewall and therefore a port needs to be left open to ensure communication, this can be taken advantage of by malicious users. Also Internet timing sources can’t be authenticated; authentication is a security measure that ensures that a timing reference is what it says it is.

Which method is best for me a radio referenced time server or one that utilises the GPS network?

This depends on location. While GPS signals are available everywhere on the planet the antennas do have to have a clear view of the sky to receive the signal, alternatively radio transmissions are limited in their availability although where available the signals can be received indoors.

How accurate are time servers?

A radio referenced network time server can provide UTC time to an accuracy of 100 microseconds, while the GPS network can fare even better with accuracies of a few milliseconds reasonably possible.

Time Servers – Using the MSF Broadcast

Time servers are essential in keeping computer networks synchronised without them many time sensitive transactions would be impossible to conduct. Time servers work by receiving a signal timing reference and distribute it to all devices on a network using the protocol NTP (Network Time Protocol). The time signal used by most time servers comes from a UTC (Coordinated Universal Time) source. UTC is based on the time told by atomic clocks and is used globally, allowing computers from across the world to be synchronized to the same time reference.

There are three methods that time servers can receive the UTC signal from. Firstly, the internet, although unsecured and without any guarantees of accuracy Internet time references are only suitable for networks where precision and security are not a concern.

The second method is via the GPS network which is available everywhere but only where an antenna has a clear view of the sky.

The third and simplest method to receive an accurate and secure UTC time reference is to use the national time and frequency broadcasts. In the UK the National Physical Laboratory transmits the British signal from Anthorn in Cumbria. This signal, known as MSF, can be received in most places in the UK although local topography can interfere with the transmission.

To receive the MSF broadcast a radio referenced NTP time server is required. This will receive the radio transmission via 65 kHz in long wave and distribute it amongst the network.
A radio based NTP server usually consists of a rack-mountable time server, and an antenna, consisting of a ferrite bar inside a plastic enclosure, which receives the radio time and frequency broadcast. The antenna should always be mounted horizontally at a right angle toward the transmission for optimum signal strength.

Similar national timing transmissions are broadcast from other countries in the US the signal is referred to as WWVB and is broadcast by the NIST (National Institute for Standards and Technology) in Fort Collins, Colorado, other systems are broadcast in Frankfurt, Germany (DCF-77), Japan (JJY) and France ( TDF).

Using A Time Server to Maintain Precise Time on Your Computer

Computer networks rely on timekeeping for nearly all their applications, from sending an email to saving data, a timestamp is necessary for computer to keep track. All routers and switches need to run at the same rate, out of sync devices can lead to data being lost and even entire connections.

All PC’s and networking devices use clocks to maintain an internal system time. These clocks, called Real Time Clock chips (RTC) provide time and date information. The chips are battery backed so that even during power outages, they can maintain time.

However, personal computers are not designed to be perfect clocks, their design has been optimized for mass production and low-cost rather than maintaining accurate time. However, these internal clocks are prone to drift and although for many application this can be quite adequate, often machines need to work together on a network and if the computers drift at different rates the computers will become out of sync with each other and problems can arise particularly with time sensitive transactions.

For some transactions it is necessary for computers to be perfectly synchronised, even a few seconds difference between machines can have serious effects, such as finding an airline ticket you had booked had been sold moments later to another customer or you could draw your savings out of a cash machine and when your account is empty you could quickly going to another machine and withdraw it all again.

Time servers are like other computer servers in the sense they are usually located on a network. A time server gathers timing information, usually from an external hardware source and then synchronises the network to that time.

Most time servers use NTP (Network Time Protocol) which is one of the Internet’s oldest protocols still used, invented by Dr David Mills from the University of Delaware, it has been in utilized since 1985. NTP is a protocol designed to synchronize the clocks on computers and networks across the Internet or Local Area Networks (LANs).

NTP utilises an external timing reference and then synchronises all devices on the network to that time.

Often time servers are synchronised to a UTC (Coordinated Universal time) source which is the global standard time scale and allows computers all over the world to synchronised to exactly the same time. This has obvious importance in industries where exact timing is crucial such as the stock exchange or airline industry.

There are various sources that a time server can use as a timing reference. The Internet is an obvious source, however, internet timing references from the Internet such as nist.gov and windows.time can not be authenticated, leaving the time server and therefore the network vulnerable to security threats.

NTP Server – Why the Need for a Dedicated Time Server

Just as your computer is only as good as the software it is running, a time server is only as useful as the timing source it uses. Time servers are similar to other servers in that they are located on a network but the primary function of a time server is to supply timing information rather than storing or routing data.

For computers a time stamp is the only point of a reference a computer can use to establish a sequence of events. Timestamps are used in everything from sending an email to debugging a system and ensuring your network is secure.

Nearly all time servers rely on NTP (Network Time Protocol) to synchronise devices once a timing source is selected Whilst it is not the only protocol designed for synchronisation it is by far the most widely used, primarily because it has been under constant development since its inception nearly three decades ago.

A NTP server works by receiving a time reference from an authoritative source, normally a UTC time source. UTC (Coordinated Universal Time) is an International timescale based on the time told by atomic clocks.

Unfortunately many administrators opt to use an Internet timing source to run their time server with. However, several studies of Internet timing references discovered that nearly two thirds were inaccurate by over several seconds (almost an eternity in the world of NTP) and those that weren’t were often too far away from a client to provide reliable accuracy.

Probably the most accurate and widely used method of retrieving a reliable time reference is to use a dedicated GPS Time Server, many national physics laboratories also broadcast the time told by their atomic clocks via long wave radio. These signals can be received by a time server if it is equipped with a radio receiver although not every country broadcasts one and the transmissions are susceptible to interference and local topography.

Once this secure UTC time reference is received the time server can then distribute the time across the network. The timestamp itself is represented as a single ascending number. The number is the amount of seconds from a prime epoch (start number) normally 01 January 1900. The time server checks the system clocks on its clients and advances or retracts the time until all machines on the network are synchronised.