The DNS Library
Technical reference for DNS concepts, infrastructure, security, and filtering.
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33 articles in six sectionsReading paths from first principles to filtering policy. Each section reads in order.
DNS Fundamentals
Core concepts including records, resolution, caching, and TTL behavior.
DNS Infrastructure & Operations
Authoritative servers, resolvers, forwarding, and network architecture.
DNS Clients & OS Behavior
How operating systems and applications handle DNS queries.
Modern DNS & Privacy
DNS over HTTPS, DNS over TLS, encrypted DNS, and privacy considerations.
DNS Security & Abuse
Threats, vulnerabilities, DNSSEC, and attack patterns.
DNS Filtering & Policy
Content filtering, policy enforcement, and protective DNS implementation.
Reference
Look-up material that supports the reading paths.
Recently Updated
Stub Resolvers: The DNS You Actually Use
An explanation of stub resolvers, the DNS components that run on endpoints and decide how name resolution behaves before any query leaves the device.
DNS Search Domains and Suffix Expansion
How operating systems modify and expand names before sending DNS queries, and why this behavior often surprises engineers.
VPNs, Split DNS, and Surprising Resolution Paths
How DNS behaves unexpectedly when traffic is split across multiple networks or trust boundaries, and why VPNs change where DNS questions are sent.
How DNS Filtering Works
A conceptual explanation of how DNS filtering fits into the DNS resolution process, and what is actually happening when a domain is blocked.
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