I have started working on an app to brute force subdomains using mutations, permutations and alterations. This will test millions of combinations again a list of DNS servers. I need a tool to keep my DNS servers list clean and fast. I didn't found anything to fit what I want at 100%, so I take dnsfaster and I change some things.

This tool will test (many times) your DNS list again a test domain to validate responses. This is useful if you want to keep your DNS list under an error rate or speed limit.

Install is quick and clean

go get github.com/bp0lr/dnsfaster

dnsfaster --domain example.com --in "dnslist.txt" --out "resolvers.txt" --tests 1000 --workers 50 --filter-time 400 --filter-errors 50 --filter-rate 90 --save-dns

this will run dnsfaster again the dns servers in dnslist.txt, testing 1000 times on each server using 50 workers, and filter out the domains with response time average > 400ms, errors > 50 and sucess rate < 90%. Use --save-dns if you want just the dns ip saved in the result file.

the original author has moved out his repo to gitlab. You can visit his version at

https://gitlab.com/jules.rigaudie/dnsfaster

thanks @jules.rigaudie for your work. :)