Controlling Search Engine Bots: A Guide to Restricting Access with Robots.txt

Search engine bots play a crucial role in indexing and ranking web pages, but there are situations where website owners may want to restrict access to certain pages or specific types of content, for example to prevent a sudden spike in the bandwidth usage. One effective way to achieve this is by utilizing the robots.txt file. In this article, we'll explore how to leverage the power of robots.txt to control search engine bot access, focusing on scenarios where access to specific pages or content, such as MP4 files, needs to be restricted.

Understanding the robots.txt File:

The robots.txt file is a simple text file that resides in the root directory of a website (e.g. the public_html directory). It provides instructions to web robots or spiders about which pages or content they are allowed to crawl and index. The file uses a specific syntax to define rules that guide search engine bots.

Basic Syntax:

The basic syntax of the robots.txt file involves specifying user-agent directives followed by rules. The user-agent is the identifier for the web crawler, and the rules indicate which parts of the website should be crawled or excluded.

Example:

User-agent: *
Disallow: /private/

In this example, the asterisk (*) denotes all user-agents, and the Disallow directive instructs bots not to crawl the "/private/" directory.

Restricting Access to Specific Pages:

To restrict search engine bots from accessing specific pages, you can use the Disallow directive with the URL path of the page you want to exclude.

Example:

User-agent: *
Disallow: /restricted-page.html

This instructs all web crawlers not to crawl the "/restricted-page.html" page.

Restricting Access to Specific Content (e.g., MP4 Files):

If you want to restrict access to specific types of content, such as MP4 files, you can use the file extension in the Disallow directive.

Example:

User-agent: *
Disallow: /*.mp4$

This prevents search engine bots from crawling any URLs that end with ".mp4".

Important Considerations:

1. Use Specific User-Agents:

   • If you want to apply rules to specific search engine bots, mention their user-agent, instead of the asterisk (*), in the robots.txt file. For example, "Googlebot" or "Bingbot".

   • Please note that some search engines have variations of their crawler bots, such as "Googlebot-Video" for their bot that crawls video files.

   • Some crawlers may ignore the global user agent (*).

   • To restrict access to a video file, you would be best to have two deny rules, one deny rule for "Googlebot" and another for "Googlebot-Video". The Google documentation explains they'll use both user-agents when indexing video files.

2. Regularly Update the File: As your website evolves, you may need to update the robots.txt file to reflect changes in content or page structure.

3. Test Changes: Before deploying significant changes to your robots.txt file, it's advisable to use Google's Search Console or other webmaster tools to test the impact on crawling and indexing.

Conclusion:

The robots.txt file is a powerful tool for controlling how search engine bots interact with your website. By strategically using the Disallow directive, you can restrict access to specific pages or content, providing you with the flexibility to manage what information is made available to search engines. However, it's essential to approach this with caution, as misconfigurations can impact your site's visibility on search engine results pages. Always review and test your robots.txt file to ensure it aligns with your website's goals and content management strategy.

Updated by SP on 24/11/2023