December 2006
Intermediate to advanced
1188 pages
72h 8m
English
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NTP Server Configuration
Problem
You want to configure the NTP server to provide time to your routers.
Solution
To configure an NTP server to provide time to your network, use the commands in Example 14-1.
Example 14-1. /etc/ntp.conf
#Define NTP Servers # server 10.1.1.1 server 10.2.2.2 server 10.3.3.3 # #Define Access Control restrict 10.1.1.1 nomodify notrap nopeer noquery restrict 10.2.2.2 nomodify notrap nopeer noquery restrict 10.3.3.3 nomodify notrap nopeer noquery # #Define NTP Drift File driftfile /var/log/ntp.drift
Warning
The NTP servers used in this example are fictitious. Please read the Discussion section to learn how to locate publicly available NTP servers.
Discussion
To find publicly available NTP servers to synchronize to, perform an nslookup on domain name pool.ntp.org. This DNS entry contains a number of Stratum 2 NTP servers that have agreed to participate in the DNS round robin group. Please be sure to perform the nslookup yourself to ensure you choose active and accurate NTP servers. The ones listed in the following example may have grown stale since the publication of this book:
Freebsd% nslookup pool.ntp.org
Server: dns.oreilly.com
Address: 172.25.1.99
Non-authoritative answer:
Name: pool.ntp.org
Addresses: 194.231.42.100, 216.52.237.151, 64.81.87.189, 65.111.164.224
66.17.252.26, 66.180.134.50, 67.128.71.75, 72.21.46.202, 80.190.241.157, 84.16.227.201, 84.45.18.237, 139.140.181.133
Freebsd%We strongly recommend that you use the IP addresses, since the restrict commands ...
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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.
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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.