Where are my static application files of Oracle APEX?

Ever got the error that there's an issue with your environment because the Application Express files have not been loaded when you try to open Oracle APEX in your environment?

Since the Announcement of the availability of Oracle APEX Static Resources on a Content Delivery Network I typically configure APEX to use the CDN.

Steps to do so for the entire environment:

• Navigate to the apex/utilities subdirectory from the directory you unzipped APEX to
• Connect to your database as the SYS user
• Run:  @reset_image_prefix.sql
• when prompted for the image prefix, enter the correct path, e.g. https://static.oracle.com/cdn/apex/18.2.0.00.12/

Now, when I got the above error, I forgot which images folder APEX was using. Was there an issue with the connection to the CDN, was it a local issue?

Below is how I found out how the APEX images directory was configured and if it was using the CDN or local files.
Connect as SYS in a SQL window (SQLcl, SQL Developer, SQL Plus, ...):

SQL> set serveroutput on
SQL> begin
  2  dbms_output.put_line(apex_180100.wwv_flow_image_prefix.g_image_prefix);
  3  end;
  4  /
/i/

PL/SQL procedure successfully completed.

SQL> begin
  2  dbms_output.put_line(apex_180200.wwv_flow_image_prefix.g_image_prefix);
  3  end;
  4  /
https://static.oracle.com/cdn/apex/18.2.0.00.12/

PL/SQL procedure successfully completed.

Above you see that in APEX 18.1 the /i/ directory is used on the local web server.
On APEX 18.2 the CDN is being used.

Note: whenever you run the above command change to the correct APEX user (version), so for APEX 19.1 you use apex_190100.