I'm tasked to configure our domain to use DNSSEC. We currently use AWS Route 53 as both our registrar and DNS hosting provider. According to the AWS documentation, Route 53 supports DNSSEC at both of these services. As far as I understand, the whole process of validating DNS queries belongs to the servers, from the recursive resolver to the TLD domain servers. My current project involves IoT devices, connected using different ISPs, which don't have any convention in terms of the recursive resolver server to use (but this could be changed). Given this scenario:
Should the recursive resolver server used be chosen based on its capability to validate DNSSEC? My understanding is that the answer is yes, otherwise DNSSEC would be meaningless.
Does it make sense to also validate the response from the recursive resolver at the client level? Is there a risk of having a MITM attack at that level? The agent installed in the IoT devices is coded in Java but I haven't found any well known client capable of validating DNSSEC.