Detecting hosting companies

#1
I am conducting research where I have a list of "ranges" which may or may not host websites. If a range has many websites there is good chance that the overall company may be a hosting company (no official definition of what that figure should be).

I am trying to ascertain how many domains/websites I need to analyse to make an accurate decision whether a company is a hosting company. There are over 350m different websites (which I do not have complete access to as a single list!) which host on (at least 1 but maybe multiple) of about 450k ranges (where 1 or more ranges may belong to one company).

To do this I see 2 possible ways:
  1. Assuming a sample size of 16641, I survey 16641 websites and can be 99% confident that if a range is returned with a website - it is a hosting company. However just because a range hosts say 1 website, that doesn't make it a hosting company - it may be I've just found a one off.
  2. I look at each group of ranges (Amazon for example may have 10's of different ranges) and as long as I have at least 16641 websites belonging to Amazon's range, I can be 99% confident that company is a hosting company.
I am trying to use Sampling/Surveying as my answer but if I'm missing something please let me know. I think option 2 is probably correct but am not sure.