Many of us navigate life each day with a smartphone. And on that smartphone is an atomic clock of sorts. No it isn't a "real" atomic clock but given a smartphone is typically connected to cell towers and/or a wi-fi network the time and day on a smartphone is generally correct. I'd be willing to bet many of you use your smartphone as your daily watch. We've pretty much come to expect we will always have the correct time (within a few seconds) available at a quick glance.
Servers should be no different. During the past four years I've been responsible for leading the technology team at Dataium. We have a fair number of servers which make up our instrastructure, from basic CentOS virtual machines to clusters of database servers running open and closed source database packages. One thing we figured out early on was just how important it was to ensure our various machines have the proper day, time, and time zone configured. There are so many different reasons why this is important and we've been bitten several times when we deployed a new machine and forgot to ensure time synching was set up.
In this short post I cover how to install NTP (Network Time Protocol) a daemon which runs on a Linux box and keeps the system clock up to date. I also cover a few things I've run into over time in installing and using NTP. This post, like so many of my others, is geared specifically to CentOS but the principles can be applied to other Linux distributions such as Ubuntu.