Comodo's SecureDNS service conducts malicious-website filtering to block phishing, malware-carrying sites, and other known dangerous websites before they can infect you. This DNS-based service is similar to OpenDNS, which we'll discuss later.

CIS lets you adjust an array of advanced settings governing heuristics levels and other general scanning settings, as well as customizable "scanning profiles." The Firewall and Defense+ features are highly customizable, too. You can fine-tune the protection by using rules, policies, definitions of trusted files/networks, and other settings.

CIS's configuration management is very convenient for running on multiple PCs. Just configure one PC, export the configuration file, and import it to the others. All settings are backed up, including scanning profiles, security policies, and password protection.

If you want to give CIS a try, download it from the . Just prior to installing it, make sure that you have completely uninstalled any existing antivirus program and rebooted Windows to prevent any conflicts. You should also disable Windows Firewall if you choose to install Comodo Firewall when installing CIS. During the installation, the setup program will ask you whether you want to enable SecureDNS. If you plan on using OpenDNS (discussed later), don't enable SecureDNS.

Once you've installed CIS, go through all of the screens and settings, and configure it to your liking. The default settings are best for most situations; for full protection, however, you may want to consider enabling cloud scanning and rootkit scanning in the Scanner Settings of the Antivirus component. Also, discover and configure the security policies settings of the Firewall and Defense+ components.