* Tim Kindberg: > DNS clients on U receive correct results from D as expected. > But when C requests a resolution result via U, D does not reply. > > In other words, D has a setting that drops recursive requests not > originating with the requestor. The DNS protocol currently does not support that because it does not distinguish forwarded from original requests (but there is a draft which would change this). So D probably just refuses to respond to EDNS requests which U happens to send. This would also happen to C if they sent EDNS requests, too.