URL Block: How to Block Websites

Summary

• URL blocking helps schools create safer online learning environments by preventing access to inappropriate, harmful, or distracting websites while students are using the internet for educational purposes.
  
  
• Schools use both blocklists and allowlists (unblocks) to manage internet access, ensuring students can reach approved educational resources while reducing cybersecurity and classroom-management risks.
  
  
• Websites can be blocked manually on Windows and Mac devices, but content-filtering tools such as GoGuardian Admin simplify the process by allowing administrators to manage website access at scale.
  
  
• Effective website filtering supports student safety, focus, and digital learning, giving educators and administrators greater control over how technology is used in the classroom.

Educators and students now have access to an unprecedented amount of online content and learning resources. While the internet offers valuable educational opportunities, it also presents challenges. Schools must help students find reliable information, protect them from inappropriate or unsafe content, and minimize distractions that can interfere with learning.

How do we know which sites have accurate information? How do we know which are safe to access? How can we ensure students access this information appropriately? Even seemingly harmless sites may contain videos, pictures, and other content that can be a distraction to the learning environment and also put the school’s network at risk.

To prepare students for an increasingly tech-reliant workplace, technology use is now deeply integrated in the classroom. In order to make sure learners reap the benefits of the internet, certain websites must be blocked either by private networks or by search engines such as Google. This list of blocked sites is called a URL block.

Schools often combine URL blocking with broader web and content filtering strategies to ensure students can access educational resources while minimizing distractions and exposure to harmful content.

What is a URL block?

A URL block is a list of sites that are deemed unfit to show to a user. Every day, Google algorithms scan thousands of websites and quarantine them if they’re not secure. Anti-virus and other search engines will also flag unsafe sites. Although this keeps the general public safe, districts need something more than just virus protection.

GoGuardian Admin creates a URL block that’s tailored for schools to help protect students while they learn online and keep them focused. Administrators can block websites, preventing learners from accessing harmful, inappropriate, or distracting content in the classroom.

How to know if a site is blocked

How do you know if Google has blocked a website? When you type in a URL and hit enter, you’ll see a red screen and a message that says, “This site may harm your computer.” Different browsers may display different messages, such as:

• “The site ahead contains malware.”
• “Suspected Malware Site”
• “Report Attack Page!”
• “This site has been reported as unsafe.”

What is an unblocked website?

Sometimes, instead of choosing websites to block, it’s easier to allow access to only a few select sites on your school’s cybersecurity list. This is called an unblock. Administrators must first approve programs, IP addresses, and email addresses, and grant system access before anyone can access websites. Anything not on the unblock list is blocked. One advantage of an unblock is that school administrators can customize them based on their unique needs.

How to block websites on Windows

You can manually block websites on your computer. However, this process is tedious and time-consuming because you’ll need to block each site individually.

Gadgets 360 provides a series of steps that you’ll need to take to manually block harmful websites on Windows:

1. Check for administrator access on your computer by going to C:\Windows\System32\drivers\etc\ in an administrator account

2. Open Notepad from the file named “hosts.” Make sure the bottom two lines say "# 127.0.0.1 localhost" and "# ::1 localhost"

2a. If you’re unable to edit the file, right-click the file labeled “hosts” and select Properties. Click the Security tab, select the administrator account, and click Edit.

2b. Select the account again in the pop-up, and check Full control. Click Apply > Yes. Click OK in all pop-ups.

3. At the end of the file, you can add the addresses of websites to block. Simply add a line at the end of the file, with 127.0.0.1 and then the name of the site you want to block. This will redirect the site's name to your local computer.

4. You can block as many sites as you want this way, but you can only add one per line.

5. Repeat this step until you've added all websites you want to block.

6. Now close the hosts file and click Save. Reboot your computer for the changes to take effect. Those websites are now blocked.

How to block websites on Mac

If you’re using a Mac, the process from Gadgets 360 is a bit shorter, but nonetheless time-consuming.

1. Check for administrator access on your Mac. Open Terminal, which you can find under /Applications/Utilities/Terminal.

2. Type “sudo nano /etc/hosts” and press enter. Enter the user (login) password when prompted.

3. This will open the file /etc/hosts in a text editor. Type the name of the website in a new line in this format "127.0.0.1 www.blockedwebsite.com" (minus the quotes). For each website you want to block, start a new line and type the same command with only the name of the website being replaced. When done, press control+x and then Y to save changes.

4. Type in the command sudo dscacheutil -flushcache and press Enter, or restart your machine to make sure the websites are blocked.

How to block or unblock websites using GoGuardian Admin

1. To add a site to your custom block or unblock, enter the URL in the box provided and hit the block/unblock button.
   
   
2. Once added, it will appear at the bottom of the list.

You can suggest websites to GoGuardian Admin’s categories after adding the site to your own block list. If the site hasn’t been categorized yet, a menu will appear asking to help improve the block by adding it to a category. Students who land on a blocked website or page will see a message that the page is restricted. When combined with effective classroom management strategies, website blocking helps educators keep students focused on learning objectives without constantly overseeing individual devices.

Teachers have the ability to lock a student’s browser during an active classroom session using the "Lock Screen" command. The command is designed to unlock at the end of the session, but if a student joins a new session before the first session ends, they will remain locked.

The Lock/Unlock Screen command can be issued by any teacher, so if a student joins your session in a "browsing disabled" state, you can quickly lock their screen by selecting the student and issuing the "Unlock Screen" command.

You can also use keywords to find websites, as well as upload your own CSV to add to a block or unblock. To do this, select “Add by CSV.”

How to remove a site from a URL block

To remove a site from your block or unblock, click the red trash can located to the right of the URL when hovering over it. This is an option only available to GoGuardian users.

How to block websites using a Chrome Extension

Frequent users of the Chrome browser can block sites by simply using a Chrome extension. Block Site is an extension available on the Chrome web store that lets you download and install a plugin. After adding this extension, click on the “block website” option on the top right of the browser whenever you come across a site you want to restrict access to.

Blocked websites: Sites that are traditionally blocked

• Streaming music and videos (Examples: YouTube, Netflix, Disney+)
• Social media (Examples: Facebook, Twitter, Instagram, TikTok)
• Pornography (Examples: RedTube, Pornhub)
• Non-educational media (Examples: People.com, ESPN)

How do schools block websites from students?

Educators want students to learn how to access online databases and be smart researchers. Many assignments may include instructions that tell learners to search for a topic. Unfortunately, given the innumerable websites that exist, finding credible sources can prove to be tricky. By blocking sites such as Quora, Reddit, and Yahoo Answers, this eliminates many of Google’s top searches and helps keep students on-task.

Teachers and administrators can also choose to unblock only the research databases they wish students to use, such as .gov and .edu websites, for a research paper. However, with GoGuardian Admin, admins can easily create blocks and unblocks so teachers can save time for lesson planning, instructing, and guiding students.

Conclusion

Blocked websites are flagged by search engines and anti-virus companies to keep computers safe. Manually blocking websites is possible, but the steps for both PCs and Macs are tedious and long.

Unblocked websites allow users to access sites that have previously been approved, but nothing else. This limits the user experience and is not ideal for adults who must access the internet in schools. There are browser plugins that will block URLs, but for a fully customized experience for classrooms, GoGuardian Admin is best suited for those needs. Administrators can set their lists so teachers can spend more time teaching and less time keeping an eye on what students are doing on their devices.

Note: This blog was originally published on February 20, 2020, and was last updated on June 22, 2026.