The benefit of the real-time scan method is that a file is scanned with the latest virus definitions before it is used. By using this approach, viruses can be detected before they compromise data.
The following describes the virus scanning process:
When a user opens a file from the client, the vscan service determines whether the file needs to be scanned, based on whether the file has been scanned with the current virus definitions previously and if the file has been modified since it was last scanned.
If the file needs to be scanned, the file is transferred to the scan engine. If a connection to a scan engine fails, the file is sent to another scan engine. If no scan engine is available, the virus scan fails and access to the file might be denied.
If the file does not need to be scanned, the client is permitted to access the file.
The scan engine scans the file using the current virus definitions.
If a virus is detected, the file is marked as quarantined. A quarantined file cannot be read, executed, or renamed but it can be deleted. The system log records the name of the quarantined file and the name of the virus and, if auditing has been enabled, an audit record with the same information is created.
If the file is not infected, the file is tagged with a scan stamp and the client is permitted to access the file.