You may want to follow up on this email thread. IPv6 vs IPv4 performance
to m.facebook.com.
https://www.mail-archive.com/[email protected]/msg23649.html
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Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka at isc.org