NTP servers are a vital tool for any business that needs to communicate globally and securely. NTP servers distribute Coordinated Universal Time (UTC), the world’s global timescale based on the highly accurate time told by atomic clocks.
NTP (Network Time Protocol) is the protocol used to distribute the UTC time across a network it also ensures all time is accurate and stable. However, there are many pitfalls in setting up a NTP network, here are the most common:
Using the correct time source
Attaining the most suitable time source is fundamental in setting up a NTP network. The time source is going to be distributed amongst all machines and devices on a network so it is vital that it is not only accurate but also stable and secure.
Many system administrators cut corners with a time source. Some will decide to use an Internet based time source although these are not secure as the firewall will require an opening and also many internet sources are either wholly inaccurate or too far away to afford any useful precision.
There are two highly secure methods of receiving a UTC time source. The first is to utilise the GPS network which although doesn’t transmit UTC, GPS time is based on International atomic time and is therefore easy for NTP to convert. GPS time signals is also readily a
The second method is to use the long wave radio signals broadcast by some national physical laboratories. These signals, however, are not available in every country and they have a finite range and are susceptible to interference and local topography.
Organising Strata
Stratum levels describe the distance between a device and the reference clock. For instance an atomic clock based in a physics laboratory or GPS satellite is a stratum 0 device. A stratum 1 device is a time server that receives time from a stratum 0 device so any dedicated NTP server is stratum 1. Devices that receive the time from the time server such as computers and routers are stratum 2 devices.
NTP can support up to 16 stratum levels and although there is a drop-off in accuracy the further away you go stratum levels are designed to allow huge networks to all receive a time from a single NTP server without causing network congestion or a blockage in the bandwidth.
When using a NTP server it is important to not overload the device with time requests so the network should be divided with a select number of machines taking requests from the NTP server (the NTP server manufacturer can recommend the number of requests it can handle). These stratum 2 devices can ten be used as time references for other devices (which become stratum 3 devices) on very large networks these can then be used as time references themselves.