Redirect 301 old/new domain

[code4projects]

Hi all,

Three months ago I bought the domain code4projects.net and all my links to code4projects.altervista.org are redirected to the new domain. For example:

https://code4projects.altervista.org...th-kubernetes/

is now redirected to:

https://www.code4projects.net/gettin...th-kubernetes/

Now I expected, after three months, that the URLs related to https://code4projects.altervista.org disappeared from Google, but if I go in Google and insert the following line:

site:code4projects.altervista.org

I still see all the blog pages. Usually, when this occurs the redirect 301 is not correctly implemented. I did it by myself for several websites and always worked. This is the first time I have no control over this because Altervista does it by itself.

Now in Google index if you insert:

site:code4projects.altervista.org
site:code4projects.net

You see the pages of the same blog with different URLs with code4projects.altervista.org redirecting to code4projects.net. This usually if not correctly implemented could bring to mark the pages of code4projects.net as duplicated if the redirect 301 is not correctly implemented.

Can someone explain to me how Altervista redirect these pages?
Thanks

[alemoppo]

This usually if not correctly implemented could bring to mark the pages of code4projects.net as duplicated if the redirect 301 is not correctly implemented.

Can someone explain to me how Altervista redirect these pages?

How could be not correctly implemented? It's just a line in the header response that you can check by yourself. Did you notice someting wrong in the response?

Bye!