title: Exact same time on multiple computers
body: <p>I want to compute some latencies in my server-client application. I was thinking about measuring the time when I send a package from <code>client A</code>, then the time when it arrives on the <code>server</code>, and a third time when it arrives the <code>client B</code>. I was thinking about using <code>DateTime.UtcNow</code>, but then realized that it takes the system time, which will surely differ on all three machines. Since my measurement will be couple thousand nanoseconds only, surely less than 10ms, since all machines are in a network.</p>
  
  <p>Is there a way to have exact time on all three machines? Possibly without using a external server, where I have to use HTTP requests.</p>