May 2011
Intermediate to advanced
788 pages
23h 34m
English
Content preview from Network Warrior, 2nd Edition
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Chapter 38. Network Time Protocol
The Network Time Protocol (NTP) is an Internet protocol used for synchronizing a device’s clock with a reference source across a network. When accurate time is required on your networking equipment or computers, you should use NTP—in other words, you should always use it.
NTP was originally defined in RFC 958. The last documented version is version 3, which is defined in RFC 1305. To learn more about NTP, check out its home page: http://www.ntp.org.
The interesting stuff relating to how NTP really works is found in RFC 1129, which is available only in PostScript or PDF format. If you get excited when you see the type of math shown in Figure 38-1, RFC 1129 is for you.
Figure 38-1. Actual math from RFC 1129
If, like most people I know, you can’t be bothered with the math and just want to know what you need to do to make NTP work for you, read on.
What Is Accurate Time?
How do we measure time? How long is a second? Who defined how long a second is, and why does it matter? These are questions most people don’t think about. Most of us take time for granted.
Every electronic device you own, from your personal computer to your television, relies on time being accurate to a certain degree. The power in your home oscillates at 60 cycles per second (60 Hz). 1080p high-definition televisions update their screens at 60 (or 120, 240, or even 480) frames per second. Modems, ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.