This isn't quite true. One can easily verify this as follows:

• Search the public peering database page for Fakebook: https://www.peeringdb.com/search?q=facebook
• You'll see two different 5-digit numbers under the "Networks" column. These are called "autonomous system numbers" or ASNs. Think of these as the "phone number" for very large organizations on the Internet.
• Log into a public route server. A handy list is here: https://www.netdigix.com/servers.html. I won't provide a telnet tutorial here, but that's what you'll need to connect to a route server.
• Once logged in, run show bgp regexp ^.* 63293$ and show bgp regexp ^.* 32934$
• You should see a bunch of results, confirming that the FB network is still very much online.

This isn't to say that a DNS outage itself isn't devastating. It most certainly is and their share price is showing as much.

This isn't quite true. One can easily verify this as follows:

• Search the public peering database page for Fakebook: https://www.peeringdb.com/search?q=facebook
• You'll see two different 5-digit numbers. These are called "autonomous system numbers" or ASNs. Think of these as the "phone number" for very large organizations on the Internet.
• Log into a public route server. A handy list is here: https://www.netdigix.com/servers.html. I won't provide a telnet tutorial here, but that's what you'll need to connect to a route server.
• Once logged in, run show bgp regexp ^.* 63293$ and show bgp regexp ^.* 32934$
• You should see a bunch of results, confirming that the FB network is still very much online.

This isn't to say that a DNS outage itself isn't devastating. It most certainly is and their share price is showing as much.