Added ExpiresByType to .htaccess but PageSpeed Insights still states that I should "Leverage Browser Caching"

Question

I have added the following code to my .htaccess but PageSpeed Insights still shows a Leverage Browser Caching suggestion.

<IfModule mod_expires.c>
ExpiresActive on
ExpiresDefault "access 1 month"
 ExpiresByType image/x-ico "access 1 year"
 ExpiresByType image/jpg "access 14 days"
 ExpiresByType image/jpeg "access 14 days"
 ExpiresByType image/gif "access 14 days"
 ExpiresByType text/html "access 2 day"
 ExpiresByType text/css "access 2 days"
 ExpiresByType image/png "access 1month"
 ExpiresByType text/x-javascript "access 1 month"  
 ExpiresByType application/javascript "access 1 month"  
 ExpiresByType application/x-javascript "access 1 month"
</IfModule>

Despite the above, PageSpeed Insights still states that I should leverage browser caching for the following:

http://assets.pinterest.com/images/PinExt.png (60 seconds)
https://assets.pinterest.com/js/pinit.js (60 seconds)
http://0.gravatar.com/avatar/ad516503a11cd5ca435acc9bb6523536?s=60 (5 minutes)
http://1.gravatar.com/avatar/572ef8c1916a898c441306a0f75f883e?s=60&d=http%3A%2F%2F1.gravatar.com%2Favatar%2Fad516503a11cd5ca435acc9bb6523536%3Fs%3D60&r=G (5 minutes)
http://1.gravatar.com/avatar/ad516503a11cd5ca435acc9bb6523536?s=60 (5 minutes)
http://cdn.api.twitter.com/1/urls/count.json?url=http%3A%2F%2Fwww.mbaadmissiongurus.com%2Fsample-mba-sop&callback=twttr.receiveCount (13.6 minutes)
http://widgets.pinterest.com/v1/urls/count.json?url=http%3A%2F%2Fwww.mbaadmissiongurus.com%2Fsample-mba-sop&ref=http%3A%2F%2Fwww.mbaadmissiongurus.com%2Fsample-mba-sop&source=6&callback=PIN_1378214653068.f.callback[0] (14.8 minutes)
https://connect.facebook.net/en_US/all.js (20 minutes)
https://apis.google.com/js/plusone.js (30 minutes)
https://platform.twitter.com/widgets.js (30 minutes)
http://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js (60 minutes)
http://pagead2.googlesyndication.com/pagead/osd.js (60 minutes)
https://oauth.googleusercontent.com/gadgets/js/core:rpc:shindig.random:shindig.sha1.js?c=2 (60 minutes)
https://platform.stumbleupon.com/1/widgets.js (2 hours)
https://platform.linkedin.com/in.js (3 hours)
https://s2.googleusercontent.com/s2/favicons?domain_url=ExportControls.com/e-seminars (8 hours)
https://s2.googleusercontent.com/s2/favicons?domain_url=healthcare-tataaig.com/Health-Cover (8 hours)
https://s2.googleusercontent.com/s2/favicons?domain_url=worldeducationfair.com (8 hours)
https://s2.googleusercontent.com/s2/favicons?domain_url=www.Dulux.in (8 hours)
https://s2.googleusercontent.com/s2/favicons?domain_url=www.asianpaintshomesolutions.com (8 hours)
https://s2.googleusercontent.com/s2/favicons?domain_url=www.principalretirementindia.com (8 hours)

Answer 1

All of the listed resources seem to be external. You cannot add/modify headers and/or caching behavior in general for external resources, hence there is nothing you can to about that.

Just make sure that all resources under your control (coming from your server(s) and or CDN) properly leverage caching.