Why Bother Using a NTP Time Server?

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Keeping computers synchronized on a network is vitally important, especially if the network in question deals with time sensitive transactions. And failing to keep a network synchronized can cause havoc leading to errors, vulnerabilities and endless problems with debugging.

However with the amount of online time servers available from reputable places such as NIST or Microsoft it is often queried as to why computer networks need to be synchronised to an external NTP time server.

These dedicated NTP devices are often seen as an unnecessary expense and many network administrators simply forgo them and connect to an online time server, after-all, it does the same job doesn’t it?

Actually there are two major reasons why NTP time servers are not only important but essential for most computer networks and to overlook them could be costly in many ways.

Let me explain. The first reason why an external NTP server is important is accuracy. It’s not that internet time sources are generally inaccurate (although many are) but there is the question of distance the time reference has to travel. Furthermore, in times when the connection is lost -whether it’s because of a local connection fault or the time server itself goes down – the network will start to drift until the connection is restored.

Secondly and perhaps most important is the security issues involved in using an Internet time source. The main problem is that if your connection to a time server through the then a open port (UDP 123 fro NTP requests) has to be left open, And as with any open port that can used as a gateway for malicious software and users.

The reason dedicated NTP time servers are essential for computer networks is that they work completely independently and external to the network’s firewall. Instead of accessing a time source across the Internet they use either GPS or radio transmissions to get the time. And in doing so they can provide accurate time all the time without fear of losing a connection or allowing a nasty Trojan through the firewall.

When Time is Money Accuracy Matters

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We live in a fast paced world where time matters. In some industries even a second can make all the difference. Millions of dollars are exchanged hands in the stock exchange each second and share prices can rise or plummet.

Getting the right price at the right time is essential for trading in such a fast paced money market and perfect network time synchronization is the essential to be able to make that happen.

Ensuring every machine that deals in stocks, shares and bonds has the correct time is vital if people are going to trade in the derivatives market but when traders are sat in different parts of the world how can this possibly be achieved.

Fortunately Coordinated Universal Time (UTC), a global timescale developed after the development of atomic clocks, allows the same time to govern every trader, regardless of where they are in the world.

As UTC is based on atomic clock time and is kept accurate by a constellation of these clocks, it is high reliable and accurate. And industries like the stock exchange use UTC to govern the time on their computer networks.

Computer network time synchronization is achieved in computer networks by using the NTP server (Network Time Protocol). NTP servers receive a source of UTC from an atomic clock reference. This is either from the GPS network or through specialist radio transmissions (it is available through the internet too but is not as reliable).

Once received, the NTP server distributes the highly accurate time throughout the network, continually checking each device and workstation to ensure the clock is as precise as possible.

These network time servers can keep entire networks of hundreds and thousands of machines in perfect synchronization – to within a few milliseconds of UTC!

Configuring a Network to use a NTP Server Part one: Finding a Time Source

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Keeping your network synchronized with the correct time is crucial for modern networking. Because of the value of timestamps in communciating globally and across multi-networks, it is imperative that every machine is running a source of UTC (Coordinated Universal Time).

UTC was developed to allow the entire global community to use the same time no matter where they are on the globe as UTC doesn’t use time-zones so it allows accurate communication regardless of location.

However, finding a source of UTC is often where some network administrators fall down when they are attempting to synchronize a network. There are many areas that a source of UTC can be received from but very few that will provide both accurate and secure reference to the time.

The internet is full of purported sources of UTC, however, many of them offer no where near their acclaimed accuracy. Furthermore, resorting to the internet can lead to security vulnerabilities.

Internet time sources are external to the firewall and therefore a hole has to be left open which can be taken advantage of by malicious users. Furthermore, NTP, the protocol used to distribute and receive time sources, cannot instigate its authentication security measure across the internet so it is not possible to ensure the time is coming from where it is supposed to.

External sources of UTC time are far more secure. There are two methods used by most administrators. Long wave radio signals as broadcast by national physics laboratories and the GPS signal which is available everywhere on the globe.

The external sources of UTC ensure your NTP network is receiving not just an accurate source of UTC but also a secure one.

Time Server Basic Questions Answered

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What is a time server?

A time server is a device that receives and distributes a single time source across a computer network for the purposes of time synchronization. These devices are often referred to as a NTP server, NTP time server, network time server or dedicated time server.

And NTP?

NTP – Network Time Protocol is a set of software instructions designed to transfer and synchronize time across LANs (Local Area Network) or WANS (Wider Area Network). NTP is one of the oldest known protocols in use today and is by far the most commonly used time synchronization application.

What timescale should I use?

Coordinated Universal Time (UTC) is a global timescale based on the time told by atomic clocks. UTC doesn’t take into account time zones and is therefore ideal for network applications as in principle by synchronizing a network to UTC you are in effect synchronizing it to every other network that utilises UTC.

Where does a time server receive the time from?

A time server can utilise the time from anywhere such as a wrist watch or wall clock. However, any sensible network administrator would opt to use a source of UTC time to ensure the network is as accurate as possible. UTC is available from several ready sources. The most used is perhaps the internet. There are many ‘time servers’ on the internet that distribute UTC time. Unfortunately, many are not at all accurate an in using an internet time source you could be leaving the network vulnerable as malicious users can take advantage of the open port in the firewall where the timing information flows.

It is far better to use a dedicated NTP time server that receives the UTC time signal external to the network and firewall. The best methods for doing this is to either use the GPS signals transmitted from space or the national time and frequency transmissions broadcast by several countries in long wave.

A Guide to Using a GPS Clock

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The Global Positioning System much loved by drivers, pilots and sea-farers as a method of finding location offers much more than just satellite navigation information. The GPS system work by using atomic clocks that broadcast signals that are then triangulated by the computer in a satellite navigation system.

Because these atomic clocks are highly accurate and don’t drift by as much as a second even in a million years, they can be utilised as a method of synchronizing computer systems. GPS time, the time relayed by the GPS atomic clocks, is not strictly speaking the same as UTC (Coordinated Universal Time), the world’s global timescale, but as they are both based on International Atomic Time it can easily be converted. (GPS time is actual 17 seconds slower than UTC as there have been 17 leap seconds added to the global timescale since the GPS satellites where sent in to orbit).

A GPS clock is a device that receives the GPS signal and then translates it into the time. Most GPS clocks are dedicated time servers too as there is little point in receiving the exact time if you are to do nothing with it. GPS time servers use the protocol NTP (Network Time Protocol) which is one of the internet’s oldest protocols and designed to distribute timing information across a network.

A GPS clock, or GPS time server works by receiving a signal directly from the satellite. This unfortunately means the GPS antenna has to have a clear view of the sky to receive a signal. The time is then distributed from the time server to all devices on the network. The time on each device is regularly checked by NTP and if differs to the time from the GPS clock then it is adjusted.

Setting up a GPS clock for time synchronization is relatively easy. The time server (GPS clock) are often designed to fill a 1U space on a server rack. This is connected to the GPS antenna (usually on the roof) via a length of coax cable. The server is connected to the network and once it has locked on to the GPS system it can be set to begin synchronizing the network.

Computers, Communications, Atomic Clocks and the NTP Server

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Time synchronisation on computer networks is often conducted by the NTP server. NTP time servers do not generate any timing information themselves but are merely methods of communicating with an atomic clock.

The precision of an atomic clock is widely talked about. Many of them can maintain time to nanosecond precision (billionths of a second) which means they won’t drift beyond a second in accuracy in hundreds of millions of years.

However, what is less understood and talked about is why we need to have such accurate clocks, after-all the traditional methods of keeping time such as mechanical clocks, electronic watches and using the rotation of the Earth to keep track of the days has proved reliable for thousands of years.

However, the development of digital technology over recent years has been nearly solely reliant on the ultra high precision of an atomic clock. One of the most widely used applications for atomic clocks is in the communications industry.

For several years now telephone calls taken in most industrialized countries are now transmitted digitally. However, most telephone wires are simply copper cables (although many telephone companies are now investing in fibre optics) which can only transmit one packet of information at a time. Yet telephone wires have to carry many conversations down the same wires at the same time.

This is achieved by computers at the exchanges switching from one conversation to another thousands of times every second and all this has to be controlled by nano-second precision otherwise  the calls will become out of step and get jumbled – hence the need for. Atomic clocks; mobile phones, digital TV and Internet communications use similar technology.

The accuracy of atomic clocks is also the basis for satellite navigation such as GPS (global positioning system). GPS satellites contain an onboard atomic clock that generates and transmits a time signal. A GPS receiver will receive four of theses signals and use the timing information to work out how long the transmissions took to reach it and therefore the position of the receiver on Earth.

Current GPS systems are accurate to a few metres but to give an indication of how vital precision is, a one second drift of a GPS clock could see the GPS receiver be inaccurate by over 100 thousand miles (because of the  huge distances light and therefore transmissions take in one second).

Many of these technologies that depend on atomic clocks utilise NTP servers as the preferred way to communicate with atomic clocks making the NTP time server one of the most crucial pieces of equipment in the communication industries.

How to Synchronise Your PC to an Atomic Clock

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The world’s technologies have advanced dramatically over the last few decades with innovations likes the internet and satellite navigation having changed the way we live our lives.

Atomic clocks pay a key role in these technologies; their time signals are what are used by GPS receivers to plot location and many applications and transactions across the internet if it wasn’t for highly precise synchronisation.

In fact a global timescale has been developed that is based on the time told by atomic clocks. UTC (Coordinated Universal Time) ensures that computer networks across the globe can be synchronised to the exact same time.

Synchronising computers and networks to atomic clocks is relatively straight forward thanks in part to NTP (Network Time Protocol), a version of which is included in most operating systems and is also thanks to the number of public NTP servers that exist on the internet.

To synchronise a Windows PC to an atomic clock is done by simply double clocking the clock on the task bar and then configuring the Internet Time tab to a relevant NTP server. A list of public NTP servers can be found at the NTP pool website.

When configuring networks to UTC however, a public NTP server is not suitable as there are security issues about polling a time source outside the firewall. Public servers are also known as stratum 2 servers which means they receive the time from another device that gets it from an atomic clock. This indirect method means that there is often a compromise in accuracy, furthermore if the internet connection goes down or the time server site then the network will soon drift away from UTC.

A far more secure and stable method is to invest in a dedicated NTP time server. These devices receive a time signal directly from an atomic clock, either produced by a national physics lab like NIST or NPL via long wave radio or from GPS satellites.

A single dedicated NTP server will provide a stable, reliable and highly precise source of UTC and allow networks of hundreds and even thousands of devices to be synchronised to NTP.

Common GPS Queries

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Is the GPS time signal the same as the GPS positioning signal?

Yes. The signals that are broadcast by GPS satellites contain time information and the position of the satellite it came from (and its velocity). The timing information is generated by an onboard caesium atomic clock. It is this information used by satellite navigation devices (sat navs) that enables global positioning. Sat Navs use these signals from multiple satellites to triangulate a position.

How accurate is GPS positioning?

Because the time signal generated by GPS comes from an atomic clock it is accurate to within 16 nanoseconds (16 billionths of a second). As light travels nearly 186 000 miles in a second this equates to around 16 feet (5+metres) which means a GPS positioning system is usually accurate to this much.

Is GPS time the same as UTC?

No. GPS time, like UTC (Coordinated Universal Time)is based on International Atomic Time (TAI) – the time told by atomic clocks. However as the GPS system was developed several decades ago it is now 14 seconds (and soon to be 15) behind UTC because it has missed out on the Leap Seconds added to UTC to calibrate for the Earth’s slowing rotation.

How can I use GPS as a source of UTC then?

Fortunately a GPS time server will convert GPS to the current UTC time, which as od 1 January 2009 will mean it has to add exactly 15 seconds.

GPS Time Server and its Accuracy from space

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The GPS network (Global Positioning System), is commonly known as a satellite navigation system. It however, actually relays a ultra-precise time signal from an onboard atomic clock.

It is this information that is received by satellite navigation devices that can then triangulate the position of the receiver by working out how long the signal has taken to arrive from various satellites.

These time signals, like all radio transmissions travel at the speed of light (which is close to 300,000km a second). It is therefore highly important that these devices are not just accurate to a second but to a millionth of a second otherwise the navigation system would be useless.

It is this timing information that can be utilized by a GPS time server as a base for network time. Although this timing information is not in a UTC format (Coordinated Universal Time), the World’s global timescale, it easily converted because of its origin from an atomic clock.

A GPS time server can receive the signal from a GPS aerial although this does need to have a good view of the sky as the satellites relay their transmissions via line-of-sight.
Using a dedicated GPS time server a computer network can be synchronised to within a few milliseconds of NTP (milli=1000th of a second) and provide security and authentication.

Following the increase use of GPS technology over the last few years, GPS time servers are now relatively inexpensive and are simple and straight forward systems to install.

Next Generation of Accurate Atomic Clocks Starts Ticking as NIST scientists unveil new strontium clock

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Those chronological pioneers at NIST have teamed up with the University of Colorado and have developed the world’s most accurate atomic clock to date. The strontium based clock is nearly twice as accurate as the current caesium clocks used to govern UTC (Coordinated Universal Time) as it loses just a second every 300 million years.

Strontium based atomic clocks are now being seen as the way forward in timekeeping as higher levels of accuracy are attainable that are just not possible with the caesium atom. Strontium clocks, like their predecessors work by harnessing the natural yet highly consistent vibration of atoms.

However, these new generations of clocks use laser beams and extremely low temperatures close to absolute zero to control the atoms and it is hoped it is a step forward to creating a perfectly precise clock.

This extreme accuracy may seem a step too far and unnecessary but the uses for such precision are many fold and when you consider the technologies that have been developed that are based on the first generation of atomic clocks such as GPS navigation, NTP server synchronisation and digital broadcasting a new world of exciting technology based on these new clocks could just be around the corner.

While currently the world’s global timescale, UTC, is based on the time told by a constellation of caesium clocks (and incidentally so is t he definition of a second as just over 9 billion caesium ticks), it is thought that when the Consultative Committee for Time and Frequency at the Bureau International des Poids et Mesures (BIPM) next meets it will discuss whether to make these next generation of atomic clocks the new standard.

However, strontium clocks are not the only method of highly precise time. Last year a quantum clock, also developed at NIST managed accuracy of 1 second in 1 billion years. However, this type of clock can’t be directly monitored and requires a more complex scheme to monitor the time.