I was one of those who voted to close, so I suppose that I should respond.
Firstly, the other question you reference is an old question (Oct 2010), and SF's rules on topicality have changed over time. Moreover, a moderator has since marked it off-topic as well, so that argument holds no water.
As to why I found your question off-topic, it was because this is an absolutely standard job for a professional sysadmin. We test development systems all the time by suborning the local DNS in order to allow access to a local test server using name-based virtual hosting; being a standard skill, in a business environment this is therefore a non-question.
The other question you link to is summarised by one commenter as being tantamount to asking how DNS works, and that's not a suitable question for SF. Yours, I would argue, is tantamount to asking how HTTP/1.1 name-based virtual hosting works, and my feeling is that it is equally off-topic.
I'm afraid it's not our job to find you somewhere suitable to post a question that's off-topic for SF; you will need to engage with those other communities to find out if your question is suitable for them. I would guess that webmasters is a sensible place to start, but it's really only a guess; the onus is on you to do the research.