massdns

massdns is a simple high-performance DNS stub resolver targeting users who need to resolve millions or billions of domain names efficiently. Without special configuration, it achieves high resolution rates using publicly available resolvers, making it ideal for large-scale DNS operations.

It supports bulk lookups and reconnaissance tasks, providing various output formats and advanced options for filtering and processing responses. The tool is particularly useful in scenarios requiring rapid domain resolution at scale.

massdns includes options for privilege dropping, custom resolver usage, and detailed control over output, enhancing its utility in security testing environments.

massdns operates as a DNS stub resolver using high-performance techniques like busy-wait polling or epoll for handling massive parallel queries. It resolves domain names by querying specified or file-based resolvers, with configurable retry counts and fallback mechanisms. Output modes include domain lists, simple text, full text, binary, and ndjson, with advanced flags for filtering responses by code, including additional records, timestamps, and section separation.