What is DNS?

The Domain Name System (DNS) is the phone book of the Internet. When users type domain names such as ‘google.com’ or ‘nytimes.com’ into web browsers, DNS is responsible for finding the correct IP address for those sites. Browsers then use those addresses to communicate with origin servers or CDN edge servers to access website information. This all happens thanks to DNS servers: machines dedicated to answering DNS queries. The DNS resolver (also referred to as the DNS recursor) is a server that receives the query from the DNS client, and then interacts with other DNS servers to hunt down the correct IP. Once the resolver receives the request from the client, the resolver then actually behaves as a client itself, querying the other three types of DNS servers searching for the right IP.

What is RPZ?

A response policy zone (RPZ) is a mechanism to introduce a customized policy in Domain Name System (DNS) servers, so that recursive resolvers return possibly modified results. By modifying a result, access to the corresponding host can be blocked and/or redirected. RPZ is essentially a filtering mechanism, either preventing people from visiting internet domains, or pointing them to other locations by manipulating the DNS answers in different ways. RPZ provides the opportunity for DNS recursive resolver operators to be able to obtain reputational data from external organizations about domains that may be harmful, and then use that information to avoid harm coming to the computers that use the recursive resolver by preventing those computers from visiting the potentially harmful domains.

How Does Hallsville ISD Use DNS and RPZ?

To protect our staff, students and community, Hallsville ISD subscribes to several curated block lists. These lists are pointers to websites and domains categorized by the type of content they serve. HISD currently processes and filters approximately 37.5 million sites for categories such as:

• Malware
  Malware is the collective name for a number of malicious software variants, including viruses, ransomware, and spyware. Shorthand for malicious software, malware typically consists of code developed by cyber attackers, designed to cause extensive damage to data and systems or to gain unauthorized access to a network. Malware is typically delivered in the form of a link or file over email and requires the user to click on the link or open the file to execute the malware.

• Pornography
  Sites depicting or providing images, text, video, or other media types depicting erotic or sexual acts designed to cause sexual arousal including visual material containing the explicit description or display of sexual organs or activity, intended to stimulate erotic rather than aesthetic or emotional feelings.

• Hate speech
  Sites depicting or providing speech that expresses hate or encourages violence towards a person or group based on something such as race, religion, sex, or sexual orientation. Hate speech is usually thought to include communications of animosity or disparagement of an individual or a group on account of a group characteristic such as race, color, national origin, sex, disability, religion, or sexual orientation.

• Violence
  Sites depicting or encouraging the use of physical force so as to injure, abuse, damage, or destroy. Other definitions are also used, such as the World Health Organization's definition of violence as "the intentional use of physical force or power, threatened or actual, against oneself, another person, or against a group or community, which either results in or has a high likelihood of resulting in injury, death, psychological harm, maldevelopment, or deprivation."

• Illegal substances
  Sites depicting or encouraging the possession, distribution, ingestion, manufacture, sale, or delivery of substances which are prohibited under local, state and/or federal law, including any controlled substance, drug, or intoxicating compound.

• Global Deny Lists (local)
  Sites requested to be blocked by campus and district administration that do not fall into a specified category. These sites are typically deemed as time-wasting, disruptive or inappropriate for student viewing.

In addition to the categories listed above, HISD may periodically filter and/or limit access to non-educational sites and services that place undue stress on bandwidth and network resources, such as gaming networks and streaming services. To ensure resource availability during state testing windows, additional filtering and access limitations may be enforced.

Caveats and Gotchas

It goes without saying that no internet filtering system is perfect, and no filter can substitute for parental involvement. Sites will slip through that shouldn't and sites will get blocked that shouldn't. Users may report categorization errors by visiting https://rpz.hisd.com and using the "URL Test" utility from the options menu in the upper-right corner of the page. Parents and guardians should use their student's email address when reporting inconsistencies.

Hallsville ISD offers no guarantee that this system is 100% effective and accepts no responsibility for damages. Hallsville ISD is not liable for damages resulting out of the access to, the use or the inability to use websites categorized by the HISD DNS/RPZ system.