Is it necessary to own both domains if I want to forward, redirect, and/or alias a subdomain?

Question

Please forgive me (and please correct) if I misuse jargon and terminology -- web hosting, administration, etc. is new to me.

Say I want to host a site at each of the following addresses:

• http://www.aexample.com
• http://aexample.com
• http://www.a.example.com
• http://a.example.com

I would like the underlying content to be the same at each address.

Questions:

1. What is the proper approach to achieve this?
2. How many (and which) domains do I need to own? This is the crux of my confusion: Do I have to own example.com and aexample.com to achieve a.example.com or can I just add the subdomain?
3. What is the proper forwarding | redirecting | aliasing to be completed?

Answer 1

First, when you obfuscate things or for documentation purposes, please use guidance from RFC2606 to select the names to be used.

Now to get to your questions:

1. Like for any other cases you need both to set up DNS entries so that each name is resolved at the end to the server where the sites live. This is usually done through A/AAAA records or CNAME ones depending on the situation, but your question is too broad, it depends on who exactly host your DNS and your webserver. Then you need to configure your webserver to reply for the given names

2. You have to own in some way both example.com and aexample.com since you will need to modify their DNS configuration

3. There is no concept of forwarding/aliasing/redirecting here, except if you want any of the following:

   • when typing one of the name, being redirected to another one, which will show in the address bar of the browser
   • showing content from one website on another one, without changing the URL (this will be proxying).

Your questions is very broad and has no very specific constraints so you should be able to find many resources explaining all of this in more details.