How an online bank knows who you are

Q: Besides entering my user ID and password, my financial institution makes me verify my identity by entering a personal identification number (PIN) that is sent via text, e-mail or phone call. Even after that, I'm always asked whether my PC is a public or private computer (it's private).

I think I'm asked all this because my PC's internet address isn't recognized. This may be because we have several computers sharing our home network, or because I've enabled DHCP (Dynamic Host Configuration Protocol), which allows our internet service provider to assign us a different address.

Can I make my PC's internet address stay the same so that it's recognized by the financial site?

Tom Krocak, New Brighton

A: These efforts to verify your identity aren't related to your PC's IP (internet protocol) address, which isn't a reliable way of proving who you are.

Instead, your financial institution is trying to keep your accounts secure by using two-factor authentication; the PIN forms a second barrier to unauthorized access. As a further security measure, you are asked if the PC is public or private to ensure that no other potential user of that PC can access your accounts.

If it's a public computer, your browser will be given a temporary cookie (a code that identifies you to the financial institution's website). That cookie will disappear once your internet session ends.

Why don't financial institutions rely on IP addresses to identify their customers? One reason is that most consumers have "dynamic" IP addresses that are assigned and occasionally changed by an internet service provider (you opted in to that by enabling DHCP for your home network). Another is that many consumers have multiple computers sharing a home network; to anyone on the internet, those computers all appear to be using the same IP address.

The primary reason a consumer might want a static, or unchanging, IP address is to run a website from home (the website is easier to manage if its underlying IP address never changes). Note: Internet service providers, including Comcast and CenturyLink that serve your area, charge additional fees for a static IP address.

Q: I have two printer problems. In one case, a Windows 7 PC can't print PDF documents to a Canon MF6160dw printer. In another, a Windows 7 PC can't receive documents scanned by a Brother DCP-7065DN printer; the error message is "CC4-205-00000000." What can I do?

Jackie Welke, Altoona, Wis.

A: There are several different types of PDF files, and that can cause printing problems. One solution is to convert all PDF files to a single type, called PDF/X (see tinyurl.com/y72aerjc and tinyurl.com/ydc3aznc).