Using hosts file to register DNS C-name

I’ve been using the hosts file for ages, and I actually also have been using this “feature” before without knowing it worked like this. But when I think about it, it makes sense and is quite coolJ.

So let’s get started. Often we use hosts file to test new implementations, changes to existing system and so on. But when the changes involve c-name record requirement (for example to Office365), how do we test that?

It is as simple as this

As you see from the example above, I do a normal A record (a-record.msitpros.com). But after that I register a c-name.msitpros.com to the same line. I used to believe that the record would be resolved to the same IP. But as you can see, c-name.msitpros.com resolves to a-record.msitpros.comJ

So for let’s say test autodiscover, we can do

How cool is that?J