On Fri, 20 Aug 2021 01:32:16 +0700, Pirawat WATANAPONGSE via NANOG said:
1. How-to monitor whether some outsiders are putting our IP addresses into their A/AAAA records without me knowing about it?
So some bozo sticks an entry in their DNS that says bozo-entry.example.com A your.ip.address.here Who cares? What problem does this cause? You'd never even know it unless somebody/something actually *uses* the DNS record - which will result in traffic to the address. And at that point, you usually don't care what DNS entry was used, except for the case of a webserver serving multiple names and using different TLS certificates for each name.
2. How-to monitor whether some outside websites are just ‘shells’, with contents actually being hosted by our servers without me knowing about it?
Again - what actual problem are you trying to solve here? If you're being used as a cache or backend site and don't know it, you have *bigger* problems.