To scan a domain for third-party domains it serves content from and to detect site redirections, what tool should you use?

To scan a domain for third-party domains it serves content from and to detect site redirections, you can use various online tools and browser extensions, or you can run specific commands in the terminal. Here's how you might proceed:

1. Online Services: You can use online services like BuiltWith or SimilarWeb, which can give you information about the technologies used by a website, including the third-party services it employs.

2. Browser Extensions: Extensions such as Ghostery or uBlock Origin can show you the trackers and third-party domains that are being loaded when you access a website.

3. Developer Tools: Modern web browsers come with built-in developer tools that can be accessed by pressing F12 or right-clicking on a web page and selecting "Inspect." The "Network" tab within the developer tools will show you all the requests made by the page, including those to third-party domains.

4. Command-Line Tools: For more technical users, tools like `curl` or `wget` can inspect headers and redirections. For example, using `curl -I http://example.com` will show you the headers for the initial response from that domain, which may include redirection information.

5. Specialized Security Tools: Tools such as OWASP ZAP (Zed Attack Proxy) and Burp Suite can monitor the traffic between your browser and the internet, revealing third-party domains and redirections.

6. DNS and Network Monitoring Tools: Programs like Fiddler, Wireshark, or even simple DNS query tools like `nslookup` and `dig` can help you see the underlying DNS queries made by your system, which would include queries to third-party domains.

Remember that the particular tool you choose will depend on your technical expertise and the depth of information you are seeking.