 All right, whether you have a PC or Mac, it has a built-in firewall. But how do you know if it's really working? Well, here's the million-dollar question. You want to go to a free browser test called Shields Up. It's going to tell you the answer for free. Once again, that's Shields Up. It's at GRC.com. Once again, GRC.com. Hey, stay right where you are. We have more of your phone calls coming up you don't want to miss. Listen to the Don Bongino Show, weekdays from 3 to 3 on WTCN.