The first filtering method is DNS blocking. The acronym DNS stands for “Domain Name Service.” Essentially, every device on the Internet has an address. However, those addresses are not necessarily easy to remember by humans. An Internet address is a set of four numbers separated by periods where each individual number is a number between 1 and 255. So, an Internet address might look something like this: 174.121.19.22. Actually, at the time this article was published, that was the address of the server Teens-4-Christ was hosted on. So, which is easier to remember: Teens-4-Christ.org or 174.121.19.22? The DNS is a database of every domain name (Teens-4-Christ.org) which maps that name to the proper server’s address (174.121.19.22). It is like saying I am going to the White House as opposed to saying I am going to 1600 Pennsylvania Ave, Washington, DC. The term “White House” becomes a friendly name for the physical address. Likewise, “Teens-4-Christ.org” is a friendly name for the physical address “174.121.19.22.”

So, when you type a human readable name such as “www.Teens-4-Christ.org” into your web browser, how does your computer know where to find that address? Your computer must ask a DNS server. In most cases, your Internet service provider, or ISP, provides you with access to their DNS Server. However, you can change that. So, suppose your computer asks for, hypothetically, “somepornsite.com” your ISP will dutifully return the address of that site. However, if you were using a DNS server which knew you didn’t want to go to porn sites. Instead of returning the correct address of the unwanted site, it would send you an address which may point to nothing or an address which may point to an error page. Your computer doesn’t know the difference. It will receive an address and try to load whatever content is at that address.

Using DNS blocking requires no software to be installed on the device and it does not require any external hardware. It does, however, require some technical knowledge to implement. It can also be easily defeated by a modestly savvy user. One example of a DNS filtering service is OPENDNS (www.opendns.org). DNS filtering has the advantage of working on any device.