Caching: what to improve?

[tobee]

Results were:

Quote:Leverage browser caching of static assets: 84/100

WARNING - (1.3 hours) - http://wxyz.int-x3.letsencrypt.org/
WARNING - (6.3 days) - http://gp.symcd.com/
WARNING - (6.3 days) - http://gp.symcd.com/
WARNING - (6.3 days) - http://gp.symcd.com/
WARNING - (6.3 days) - http://gp.symcd.com/
WARNING - (6.3 days) - http://gp.symcd.com/

What can I do here?

[tobee]

Seems that the symcd.com "errors" stem from using CDN (MaxCDN for bootstrap and fontawesome; googleapis for jquery) So there is nothing I can do.