Using some creative google hacks I put together a disorganized list of well over a million domain names, I then used a regex to rip out the subdomains and then sorted them by frequency. You can also use this data-mangling feature by using using this simple command: python subroute.py -f full.html > my_subs.txt
I used this feature to create subs.txt which contains 31280 subdomains. subs_small.txt was stolen from fierce2 which contains 1896 subdomains.
Having a list of resolvers (resolvers.txt) is best for a multi-threaded application because most dns resolvers have rate-limiting by default. This feature is for speed.
Easy to install : You just need http://www.dnspython.org/ and python2.7, should work under any operating system: bsd, osx, windows, linux…
Under Ubuntu/Debian all you need is:
sudo apt-get install python-dnspython
Easy to use: