Developer builds DNS query tool from scratch to explain protocol internals

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A developer has published a hands-on guide explaining how DNS works by building a simplified version of the dig command-line tool from scratch in C. The project, hosted on GitHub under ecekaptan/dig-from-scratch, walks through the raw byte structure of DNS packets, covering headers, flags, question sections, and answer records. A DNS lookup consists of just two packets — a query and a response — each following a fixed five-part structure with no padding or separators, using big-endian byte ordering. The 12-byte header encodes six 16-bit fields including a transaction ID, flag bits, and counts for questions and answers. The guide pays particular attention to the FLAGS field, breaking down individual bits such as Recursion Desired and Response Code to show exactly how a client and server communicate intent and status.

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