Sidewinder G2 6.1.2 Administration Guide - Glossary of Technical ...

Appendix B: Setting Up Network Time Protocol
Overview of NTP
Overview of NTP NTP provides a way to synchronize all clocks on a network, or to synchronize
the clocks on one network with those on another network. You may find NTP
useful in the following situations:
594
Figure 234: NTP serverclient
relationship
• When your internal network includes a system that already provides time
for the rest of your network.
• When, for time-critical services, it is important to synchronize your network
with a more accurate chronometer on an external network.
Important: If exact synchronization is not important to your site, you may ignore
NTP entirely. NTP is not automatically enabled during Sidewinder G2 installation,
and is active only if you configure and enable it as described later in this appendix.
This release of the Sidewinder G2 is compatible with NTP versions 1, 2, and 3.
Version 3 is the preferred version and is the default on the Sidewinder G2.
NTP servers and clients
In NTP, a server is a system that sends a time-feed to another system. (The
server is also referred to as a host.) The receiving system—the one whose
time is being set by the server—is an NTP client.
Consider the simple configuration in Figure 234 showing an NTP time server
with two NTP clients (A and B) in the same network. The NTP server supplies
the time to NTP clients A and B. Using their own NTP software, each client
system must also be set up to receive time from the server.
NTP server
(time source)
Client A Client B
The Sidewinder G2 can be set up as an NTP server or a client. Secure
Computing Corporation recommends that the Sidewinder G2 be set up as an
NTP client, receiving time from an NTP server on your internal network.