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Web Filtering: Home

Information related to technology protection measures, aka filtering.


The Children's Internet Protection Act (CIPA) requires the use of technology protection measures (filters) that protect against access to visual depictions that are obscene, child pornography, or harmful to minors. For more information on the requirements of CIPA, see the CIPA page on the Universal Service Administrative Co. web site. CIPA applies if your library receives E-rate funds. If you do not receive E-rate funds, you are not required to filter. 

Filtering FAQs

Do we have to filter for adults?

Libraries receiving E-rate funding and complying with CIPA must have filters in place for all computers owned by the library, including staff computers. Alaska libraries that do not receive E-rate funding need not filter, though it would be wise to have an internet use policy

Wait - Even staff computers? 

If your library is receiving federal funding for internet support, the filtering requirement applies to all library owned computers, including the staff computers. 

What is my library required to filter?

The filter must protect against access to visual depictions that are obscene, child pornography, or harmful to minors. 

How much content should my filter block?

What you do or do not filter should reflect your community values and input received during the public forum/meeting that you are required to have at least once. It is not necessary to block so much that it inhibits the ability of library patrons to meet their ordinary information needs. Consider unintended consequences when applying your filter settings. For example, blocking all sports would block access to information about the Iditarod. 

When may we disable a filter?

For libraries receiving E-rate funding and complying with CIPA, filters may only be disabled for adults for "bona fide research or other lawful purposes." 

Do we have to filter our Wi-Fi when patrons bring their own devices?

CIPA applies only to library-owned computers. However, Wi-Fi access should be addressed in the library's Internet Use Policy.

How do I create a good Internet Use Policy? 

If you need help in creating an Internet Use Policy, visit Children and the Internet: Sample Online Policies from the American Library Association. If you would like us to review your policy, drop us a line. 

How do I test if my filter is working?

Here are a few test websites without actual objectionable content that you can use to test if your content filter is functioning:

However, since these are test websites, they might not be blocked by all content filters. If possible, you may also want to try visiting a website with actual adult content to confirm that your content filter blocks it.

Hat tip to Dylan Baker and other staff at the Idaho Commission for Libraries for these FAQs, which have been adapted to Alaska.

Methods of Web Filtering

Web filters review every request for web pages and other computer resources, then then block anything that is unauthorized. Web filters do this by a combination of the following methods:

  • Address filtering - blocking on the basis of lists (often secret) of internet addresses.
  • Keyword filtering - blocks pages based on a check of a banned words list.
  • Filtering by service / format of content - blocking video/audio streaming, IM clients, etc, even if the surrounding page is passed by the web filter.
  • Whitelisting - Build a list of approved sites, often block anything not on approved list

Most web filtering software allows blocking of sites by subject categories using a mix and match of the methods above. 

Domain Name Service (DNS) Filtering

DNS filtering works by routing your computer's "domain name" requests through a filtering provider. That provider uses the address to decide whether to provide the page to your computer. 

Specific DNS filter suggestions from Idaho

We're sharing suggestions for DNS filters made by Dylan Baker of the Idaho Commission for Libraries because they seem useful to us. You might find the rest of his filtering guide useful as well. We're not afraid of second opinions.

Computer Based Filtering Programs

If you are only looking to filter a few computers in your home or library, a computer based web filtering program may be for you. Here are a few examples along with a buying guide. 

Router / Hardware Filtering

If you are looking to provide filtering at the level of your home / small office/library network, you may want to use a hardware solution. These pieces of hardware often function as wifi hotspots in addition to providing web filter services. The following products are examples of this type of technology. 

General Filtering Resources

Over and Under Blocking

The Alaska State Library does not endorse any specific product or policy for use as an Internet protection measure. Information provided is for reference purposes.