You can load FB buttons and stuff without affecting your site at all, even if FB has DNS issues or is blocked by a firewall
https://www.facebook.com/note.php?note_id=10151176218703920
You load the JS SDK using the "fif" pattern. If it fails to load, none of the tags like <fb:like> etc get replaced by iframes, so no errors on the page. `DOMContentLoaded` and `onload` on your page fire as usual. It's as if the site doesn't even use FB widgets
Just be aware that doing that gives FB a chance to sniff cookies, referrer and other stuff on your own page.
<sarcasm>Of course, FB is completely trustworthy with any data you give them access to, so nothing wrong will ever happen.</sarcasm>
My cached results seem to have a cname of "star.c10r.facebook.com", which works:
Non-authoritative answer:
Name: star.c10r.facebook.com
Addresses: 2a03:2880:10:8f01:face:b00c:0:1
31.13.72.23
Aliases: www.facebook.com
On a serious note: DNS issue.
The authoritative nameservers a.ns.facebook.com and b.ns.facebook.com seem to be "set up" like this a the moment:
*.facebook.com ->(cname) star.facebook.com -> no answer
facebook.com still resolves the correct (?) IPs, but www.facebook.com, developers.facebook.com, graph.facebook.com all starting to die as your DNS cache expires. That's why it still might work for some at the moment while it really is broken.