DNS enumeration with Ruby

I love Ruby and it is my goto scripting language. Even in the age of AI, I like to write short custom scripts for my tool arsenal. One way to find subdomains of a potential hacking target is to initiate a DNS zone transfer. You can use various shell tools for this, but if it is part of a process(my case), it might be easier and more flexible to just script it in Ruby. I decided to use the dnsruby gem to save some work, otherwise I would need to do a TCP connection to the nameservers myself. For the sake of demonstration, I converted my script into a command line one, that will accept 2 parameters, the host and an optional IP address of a nameserver: