Time server – Synchronisation Methods

A time server is an essential piece of equipment responsible for ensuring all devices on a computer network are running the same time. Most time servers are dedicated devices that receive a time signal, normally UTC (Coordinated Universal Time), and distribute it to all devices on a network.

Most time servers use the Internet protocol NTP (Network Time Protocol) to synchronise all devices and are often referred to as NTP servers. NTP distributes a single time source throughout the network which is normally a UTC source (Coordinated Universal Time).

There are several places a time server can receive a time signal from. The internet is an obvious source for many although online time sources are not very accurate, can be too far away to give any useful precision, and more importantly are not secure being as they are external to the firewall.

As a dedicated time server is an external device they are extremely secure and impossible for malicious users to tamper with. Dedicated time server can receive a time signal from two sources the GPS network (Global Positioning System) , a highly accurate method and available everywhere on the globe with a good view of the sky; or the specialist long wave radio transmissions broadcast by national physics laboratories.

In Europe the two main radio transmissions are the UK’s MSF signal broadcast by NPL (National Physical Laboratory) in Cumbria, England and the German DCF-77 broadcast near Frankfurt.

These long wave signals are also highly accurate and can be picked up in most neighbouring countries too. The USA has a similar system called WWVB,  transmitted by the National Institute for Standards and Technology (NIST) from Boulder, Colorado.

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

Common Time Server Questions

What is a time server?

A time server is a device that utilises a single time source and distributes it amongst a network. This enables all machines on a LAN (or WAN) to be synchronised together.

What is NTP?

Network Time Protocol is a protocol (a set of instructions) designed to distribute the time from a time server top a network.

Why do I need a time server?

It may well be that you don’t. Many small networks survive and operate perfectly without the need of a time server. However, if computers are required to do time sensitive transactions or applications then a time server is essential. Without proper synchronisation all sorts of unforeseen problems can arise and many of the online transactions that we take for granted such as seat reservation, Internet shopping, the stock exchange and even sending emails are reliant on perfect time synchronisation.

What is the best time reference to use?

A single global timescale based on the time told by atomic clocks has been developed called UTC (Coordinated Universal Time). UTC is utilised by networks all over the world. In using UTC you are in affect synchronising your network with every other network in the world that utilises UTC.

Where to I get UTC time from?

The most common and easiest location to receive UTC time is from across the Internet although Internet time sources are notoriously inaccurate. They also provide little security. Apart from the fact the time server is outside your firewall, NTP can’t authenticate these signals. Authentication is a security measure used by NTP to prevent malicious attacks that masquerade as a time server.
The most secure methods for receiving UTC time is by using either the GPS network (global positioning system), whose satellites transmit the timing information or alternatively by using specialist national time and frequency long-wave transmissions although these are not available everywhere.

Probably the most inexpensive time servers in the World!

Galleon Systems and their The NTS 4000 MSF S and the NTS 4000 GPS S are possibly the two least expensive time servers available anywhere.

They are simple to use NTP time servers receiving accurate time from the a radio time signal (MSF) or the GPS network and using NTP can provide this synchronised time via a Ethernet port to any computer, server, switch, etc that conforms to the Network Time Protocol V3. And unbelievably they can process 1,000 NTP requests per minute.

The identical looking units are attractive pieces of kit too:

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.

From the Sundial to the Time Server a Brief History of Horology

Keeping track of time is something most people take for granted, yet the science of timekeeping has a long and fascinating history.

Keeping track of time was always based on the relationship between the Earth, Moon and Sun. The first timekeeping devices are thought to be monuments like Stone Henge in the UK that would recognise the winter or summer solstice allowing early man to calculate when to plant crops.

Dividing the day up into hours and being able to keep track of them has proved more difficult to civilisations.

The first timing devices were sundials, obelisks and water clocks but it wasn’t until the development of mechanical clocks in the middle-ages that time-telling started to become more accurate.

Mechanical clocks continued to develop until the turn of the twentieth century when they were bettered in accuracy by electronic oscillators that would use the resonance of a crystal (often quartz) to keep a stable time.

While electronic clocks provided accuracy to within a second a day, the atomic clock that uses the resonance of an atom (in most cases caesium -133) and was developed in the 1950’s demonstrated millisecond accuracy – not losing a second in several thousands of years.

Now atomic clocks are approaching nano-second accuracy (one second every billion years) with new developments like strontium. The atomic clock has also made horologists realise that basing a time system on the movement of the Earth and celestial bodies is unreliable as the Earth slows and speeds up.

UTC (coordinated universal time) was developed to combat this by adding leap seconds to keep atomic time in line with GMT (Greenwich Meantime). Now computer networks all over the world can synchronise to UTC and atomic clocks by using a time server.

A time server will receive a time from an atomic clock source and synchronise an entire network to this time. Without time servers, atomic clocks and UTC, technologies such as satellite communication, the Internet and global trading would be near impossible.

Time Server Fundamentals: UTC and Atomic Clocks

The atomic clock was developed in the 1950’s and represented a huge step forward in chronology. Before the atomic clock, electronic oscillators, as used in most digital clocks and watches, were providing the best accuracy although these would drift several seconds a month.

The atomic clock used the resonance of the atom caesium -133 which had an exact oscillation of 9,192,631,770 times a second. Because of this exact oscillation atomic clocks soon offered nearnano-second accuracy in that it would take several million years before they would drift by a second.

Atomic clocks were deemed so accurate that the International System of Units (SI) defined the second as this number of oscillations of the caesium atom.

As time-telling became so accurate it was soon discovered that the rotation of the Earth was not as precise as the clocks and that to keep atomic time relevant to Greenwich Meantime (GMT) and to stop night from slowly drifting into day a new timescale was developed calledUTC (Coordinated Universal Time) which accounted for the slowing of the Earth’s spin by adding ‘Leap Seconds’.

UTC is now globally used and allows the entire world to synchronise to the same timescale. This is particularly relevant for computer networks that often have to communicate with other networks across the globe.

UTC can be received by using a time server that can either synchronise to a timing reference across the Internet or for better accuracy an d security a time server can receiveUTC time from the GPS network via a GPS antenna or by receiving national timing broadcasts, transmitted form several countries.

By using a time server that receives UTC time a computer network can be accurate to within a few milliseconds of UTC allowing cross-global communication.