How to protect subdomains from crawling?

Question

Domain Name System

Good afternoon!
I was puzzled by the question, are there any possible solutions in order to hide subdomains on the main domain name from scanning? That is to hide "A" records from direct view if I, say, have subdomains a.domain.com, b.domain.com and so on.

Answer 1

You can only block access to the IP addresses of A records of subdomains, and you cannot hide the records themselves. Or, for example, you can do not b.domain.com, but myfgfqt.domain.com. Subdomain brute force programs usually do not use complex names or the bootforcing process will take up to 4 days.

Answer 2

hide "A" records from direct view

This is from the DNS settings. The domain.com zone transfer should only be allowed for the second DNS server and denied for everyone else. If you have it, then all the norms
A scan by ip. In this case, look at fail2ban