I think this approach is needed–lean on DNS for reputation management.
But this is limited by the size of TXT records. We are using string[] when there is a more scalable map<> available.
Please see how DKIM uses DNS for this. We could allow querying arbitrary contracts using a different approach like this to get a yes/no answer:
TXT 0x1234543456543456.1._domaincontracts.example.com “yes”
And then
TXT primary.1._domaincontracts.example.com “0x1234543456543456”
to allow discovery.
Instead of eTLD+1 there is an existing infrastructure for this. Please see the Mozilla Public Suffix List (PSL). We can specify that a client will query hierarchally up to the PSL+1.