IBM Proventia Network Enterprise User Manual - page 82
Chapter 6: Defining Background Scans
82
IBM Internet Security Systems
Determining When Background Scans Run
Introduction
This topic describes two important concepts for background scanning—scanning refresh
cycles and scanning windows. These concepts control when background scans run.
Scanning refresh
cycles
A scanning refresh cycle is the maximum duration (in days, weeks, or months) of a
background scan. You define scanning refresh cycles separately for discovery and for
assessment scans in a Scan Control policy, and the cycles apply to the scans for all groups
that the policy controls.
Important points
about refresh
cycles
Refresh cycles affect scanning as follows:
●
Refresh cycles apply to background discovery and background assessment scans;
they do not apply to ad hoc scans.
●
At the end of a refresh cycle, any background scanning jobs that are still running are
stopped and do not run to completion. Their status appears as Expired.
●
The refresh cycle begins at midnight on the first day of the cycle, and the jobs for that
cycle are scheduled in the Command Jobs window at that time.
Scanning windows
Scanning windows are the hours that are available for scanning each day of the week. A
scan that runs only during scanning windows pauses when a window closes and resumes
when the window reopens.
Scans affected by
scanning windows
Scanning windows affect scans as follows:
●
Scanning windows apply to all background scans for the groups controlled by a
particular Scan Windows policy.
●
When you run an ad hoc scan, you choose whether to confine the scan to the user-
defined scanning windows.
Cycle and window
dependencies
Background scanning for a group requires a refresh cycle and one or more scanning
windows. Although you define refresh cycles and scanning windows in different policies,
they work together to define the extent of your background scans. The cycle defines the
duration, or elapsed time, of the scan; the scanning windows define the days and hours
when scanning may occur during the cycle.
Example
Figure 21 illustrates a two-week scanning refresh cycle that has different scan windows
for weekdays and for each day of the weekend. In this example, scans can run from 10:00