"This block was the result of a communication error between Zoom’s domain registrar, Markmonitor, and GoDaddy Registry, which resulted in GoDaddy Registry mistakenly shutting down zoom.us domain. "
replies(3):
Their domain expired because at some level people made some pretty boneheaded mistakes.
Whomever their actual registrar actually was (GoDaddy it seems) stopped pointing the zoom.us nameserver record (NS) at AWS Route 53 which Zoom obviously uses.
% dig +short zoom.us NS
ns-387.awsdns-48.com.
ns-1137.awsdns-14.org.
ns-1772.awsdns-29.co.uk.
ns-888.awsdns-47.net.