Trouble accessing Register.com domains from Comcast and other ISP’s

On 5/12/2020, Domain Names using register.com DNS Servers become intermittently inaccessible from Comcast internet connections. The root cause of this issue appears to be DNSSEC/EDNS compatibility between register.com and Comcast, Time Warner, Charter, and other DNS Servers.

After initial testing, Comcast DNS Servers were responding with a “Servfail” error on affected domains, which means the domain exists but the authoritative DNS…