Facebook, like many large internet companies, buys their IP blocks outright, so they show up under their AS number [0]. Facebook seems to have 3 AS numbers [1,2,3] and that IP appears in [3]

[0] https://en.wikipedia.org/wiki/Autonomous_system_%28Internet%...

[1] https://bgp.he.net/AS32934

[2] https://bgp.he.net/AS63293

[3] https://bgp.he.net/AS54115

You're going to get different results for the same queries depending on where you are in terms of DNS queries. This is not a FB thing, either. Lots of places will "steer" you towards one frontend, POP, datacenter, or whatever, in order to get you off the public Internet and onto their fabric sooner.

Run the same query from a bunch of sites with different connectivity in the same town and you might get different answers depending on who's got peering agreements with who. Then spin that query again using other places in the world and you can get even more variety.

That is, assuming the site in question has worked out a way to vary the A/AAAA records for their actual domain (as opposed to the hosts within it, like "www"). Some of them might just point it at a single POP/frontend/whatever, and when that one goes down for whatever reason... things get interesting. Not that I would know anything about that.

Using whois and BGP tools, I suspect.

Edit: https://bgp.he.net/search?search%5Bsearch%5D=facebook&commit...

    ...
    157.240.18.0/24
    ...

Also see https://bgp.he.net/net/157.240.18.0/24#_whois

Documented on https://developers.facebook.com/docs/sharing/webmasters/craw...

They're in the ARIN database. Just search for FACEBOOK-CORP

https://whois.arin.net/rest/net/NET-199-201-64-0-1

A side note. By scanning, he probably just means a Shodan search:

https://www.shodan.io/search?query=net%3A199.201.65.0%2F24&l...

Login required

Plenty of organisations (especially one of Facebook's size) tend to have their own autonomous system numbers, pretty trivial to get the ranges from BGP announcements for any given ASN.

Yes, I'd like to know this as well.