Web clock (Official times across Canada)
From: National Research Council Canada
How is the official time displayed on my screen?
The time displayed on your screen is derived from Canada's official time source: NRC's atomic clocks. Your computer or mobile device receives the official time through a periodic exchange of time-stamped messages between your device and NRC's time source. The time displayed is corrected for measured network delays. If you are in North America, the display will usually show time according to your time zone. If you are outside North America, the display will show UTC (Coordinated Universal Time – the modern implementation of Zulu time or GMT). For more information on Canadian time zones consult Time zones & daylight saving time.
The offset of the clock in your device from NRC official time is also shown ('Your local clock is ___ seconds fast / slow'). If the offset is large (i.e. thousands of seconds), check that your computer settings for the date, time zone, or daylight saving time are correct. You can adjust your device's clock manually, or have it set automatically through the use of Network Time Protocol (NTP).
The network delay is equal to one half the period of time it takes for a roundtrip exchange of messages between your device and NRC's atomic clocks. The network delay can be used to estimate the uncertainties in the displayed official time and the clock offset. In most cases, the displayed time is correct to within an uncertainty equal to the network delay. However, operating system delays may degrade the accuracy to some degree.