# blechschmidt/massdns

A high-performance DNS stub resolver for bulk lookups and reconnaissance (subdomain enumeration)

Repository: https://github.com/blechschmidt/massdns
Canonical: https://ross.abutalabs.com/products/massdns
Language: C
License: GPL-3.0
License Family: copyleft
Topics: dns, dns-resolver, dns-resolution, dns-bruteforcer, dns-client, subbrute, massdns, bulk-dns, dns-lookup, reconnaissance, subdomain
Last push: 2026-04-15T21:16:50+00:00

## Health v2 (maintenance only)
Score: 57/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 77, release rhythm 8, longevity 100
- inputs: {"age_days": 3723, "days_push": 140, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3635, forks 504 (observed 2026-08-28T04:08:12.710591+00:00)

## What it is
MassDNS is a high-performance DNS stub resolver written in C, capable of resolving millions to billions of domain names at over 350,000 lookups per second. It is primarily used for bulk DNS resolution and subdomain enumeration during reconnaissance.

## Use cases
- resolve millions of domain names in bulk
- enumerate subdomains for a target domain
- perform DNS reconnaissance during security assessments
- snoop DNS caches with non-recursive queries
- test DNS resolvers at scale
- validate large domain lists quickly

## When to choose
- you need to resolve a massive volume of DNS names quickly
- you are doing subdomain enumeration or attack-surface discovery
- you want a lightweight C tool with fine-grained resolver control

## When to avoid
- you only need occasional single-domain lookups (use dig or a library instead)
- you cannot legally or ethically use third-party open resolvers at high query rates
- you need a managed DNS API rather than a raw resolver

## Facets
- artifact type: cli-tool
- maturity: stable
- function: networking, security, developer-tools
- domain: security, networking, osint
- platform: windows, cli
- tags: dns, dns-resolver, subdomain-enumeration, reconnaissance, bulk-lookup, dns-bruteforce, command-line, linux, macos

## Member repositories
- blechschmidt/massdns (main) score 57

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:12.710591+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T18:31:50.730514+00:00, confidence not recorded.
  - readme: https://github.com/blechschmidt/massdns (fetched 2026-08-28T04:08:12.710591+00:00, sha 76822ef55647)
- Data as of 2026-08-30T08:39:29.467469+00:00.