I just updated my WP theme and ran a test and found an X for Effective Use of CDN.
I didn’t change any setting.
The plugin used is W3 Total Cache. I cleared plugin cache before testing.
Here are the test results :

Anything I can do to make good? I got an OK mark for Effective Use of CDN before I updated the theme.

Do you have a CDN that you are using (cloudflare, etc)? Is the CDN on a separate sub-domain?

Yes, I am using MaxCDN. But not sure if its on sub-domain. I did not set it up with sub-domain.

Looks like 96b1ada84e3baac616429bf8.lejgz897bo7stx.netdna-cdn.com is your CDN domain and several images are being served from there but a lot also are not (which are what got flagged).

Hi Patrick,
The images that are displayed in the above page are all the images in my landing page.
The links without attached image are not images that I have loaded. They only showed up after I updated the theme. They were not there in earlier tests.
I tried to open them but they didn’t open.
Where could they come from and what to do with them?