Guides
Explanations of core networking and web security concepts — written for developers and sysadmins who want to understand what the tools are actually measuring.
What is DNS?
How the Domain Name System translates domain names to IP addresses, and what each record type means.
What is an ASN?
How Autonomous System Numbers identify network operators and what your ASN reveals about your connection.
What is an HTTP Header?
How HTTP headers control communication between browsers and servers, and which ones matter most.
What is Content Security Policy (CSP)?
How CSP protects websites from XSS attacks by restricting what resources a page can load.
What is HSTS?
How HTTP Strict Transport Security forces HTTPS connections and prevents protocol downgrade attacks.