Noticing that the "Human Verification" image did not show, I found that the src, https://sstatic.net/stackoverflow/img/captcha-conchords-robots.jpg, shows that
sstatic.net is giving an SSL vertificate for
The URL should be corrected; the correct URL is:
which works just fine:
sstatic.net domain is a named virtual host on the same machine as
$ host sstatic.net sstatic.net has address 220.127.116.11 $ host stackoverflow.com stackoverflow.com has address 18.104.22.168 stackoverflow.com mail is handled by 40 stackoverflow.com.s9b2.psmtp.com. stackoverflow.com mail is handled by 10 stackoverflow.com.s9a1.psmtp.com. stackoverflow.com mail is handled by 20 stackoverflow.com.s9a2.psmtp.com. stackoverflow.com mail is handled by 30 stackoverflow.com.s9b1.psmtp.com.
but only one SSL cert can be used per IP address. This is why you see the wrong SSL cert being used.
cdn.sstatic.net domain is the correct domain for the Stack Exchange CDN.