Testing DNS-prefect and preconnect

At the Velocity New York conference, I learnt about resource hints using the tag. I was trying to check this on a test site. When I test the sample page on WebPageTest, I don’t see the preconnect or DNS prefetch kicking in.

Is there some kind of a heuristic that prevents the resource hint from being considered?

Here’s my WPT result:
http://www.webpagetest.org/result/151016_H0_5e43f3c7848b991d9a9dfc22b12c45e4/1/details/

I was searching through the forum posts and found this interesting. In an old post (http://www.webpagetest.org/forums/showthread.php?tid=12382), there is a reference to a site that had “dns-prefetch” resource hint enabled. I checked the site and it still has the same code.

However, when I re-run the test, DNS prefetching failed:
http://www.webpagetest.org/result/151019_2T_14F6/

Since this test was in IE, I switched the browser and ran a test on Chrome. Prefetch failed here as well:
http://www.webpagetest.org/result/151019_BG_bd28f1cbe6aedcc32e88398b48dd9910/

Now I am confused if this feature has changed in some way and hence fails to work on WPT across the browsers.

I figured out that the WPT I had already showed a preconnect. After speaking to a few others, I realized that the site I am using has so few resourced and all of them statically referenced that preconnect may not help since browser may have discovered the links normally. I tried on another site and it has worked as expected. So I am good.
http://www.webpagetest.org/result/151102_RG_d530502c3600a58643dba6305fcf981f/