save

The directory 'sava' the the test data for 'getDistinctDomain1.py' and
'getDistinctDomain2.py'
one thread with block

mainly use socket.gethostbyname() and socket.getaddrinfo() to resolve
hosts. getaddrinfo() is also available in IPv6 but gethostbyname()
doesn't.
one thread without block

this is from
'http://www.catonmat.net/blog/asynchronous-dns-resolution/'. python
build ADNS can run on linux.
read hosts from file (one thread without block)

read hosts from sys.argv[1], and write ips to sys.argv[2]. Resolve
sys.argv[3] at once. The file recorded hosts will be too big, so it need
to be read line by line(It will cost some time to do this. I don't
weather there is a method in Python which can help to read several lines
a time.) Maybe keep the hosts file small and the method 'readlines' will
help.