The firewall built into Windows Vista monitors incoming network traffic by application.
Simple DNS Plus v. 5.0
automatically adds an exception (rule) to Windows Firewall when the software is installed and should be able to communicate over the Internet without any prompts from Windows Firewall.
Simple DNS Plus v. 4.00
and earlier will cause the Windows Firewall Security Alert prompt almost immediately after you start the software:
Click the "Unblock" button to allow Simple DNS Plus to receive traffic from the Internet.
You can confirm and/or edit the firewall settings as follows.
In the Windows Control Panel, under Security, click the "Allow a program through Windows Firewall" link:
In the "Exceptions" tab, scroll down to Simple DNS Plus:
For more information, please see the following knowledge base article: