I received a notice from my third-party firewall application (Little Snitch) that when I had Facebook open, my browser (Chrome 46.0.2490.80 on El Capitan 10.11.1) was attempting to connect to "scontent.fper1-1.fna.fbcdn.net" and "scontent.fmel1-1.fna.fbcdn.net". Having never seen these particular variations on the fbcdn domain before despite daily use of Facebook and having used LS for a while, it was a little suspicious to me.
Looking up the IP addresses (188.8.131.52 and 184.108.40.206 respectively) point to Internode, an ISP located in Adelaide, Australia (I live in Australia, but not Adelaide) and AFAIK, Facebook does not use their CDN and I don't think Internode even provides such services.
But the domain is fbcdn.net. right? And if that's so, which is legit domain used by Facebook for content/cookies etc, even if the IP addresses don't resolve to Facebook or Akamai, it should be fine? Nothing suspicious?