To scan external DNS zone files, I have been copying and posting the records out into notepad, cleaning up the file and then using that file as my scan target. Is there an easier, more adaptive way to go about this?
gsa: (‘gsad --version’) 8.01
gvm: (‘gvmd --version’) 8.01
openvas-scanner: (‘openvassd --version’) 6.01
gvm-libs: 5.32
Operating system: Ubuntu 18.04
Kernel: (‘uname -a’) 4.15.0
Installation method / source: Source
Just make a zone transfer, dump the zone and run a GMP script 
Thanks for the suggestion! Sadly, we are on Route 53 at AWS who seemingly do not support zone transfer. Guess I’ll stick to the old method! 
If you can copy them into a notepad, you can parse them and run a GMP script. I don´t know your managed service, but there must be a way to query your zone and update it.
I probably won’t get to this for another week or so but for others faced with this quandary, the below code should be able to extract the needed info via API.