[resolv.rb, help] Can you give me an example?

Hello,

I'm trying to write some code with Ruby. I need to write a DNS resolver. I saw a resolv.rb but there is simple example that I can take. Specifically, I need:

- Create object r (that resolvs my dns): something like r = Resolver.new()
- Put hostname and ip in this object: something like r.add(hostname, ip)
- Consult if this object knows anything about a specific hostname: something like r.query(hostname) --> ip
  and consult if this object knows anything about a specific ip: something like r.query(ip) --> hostname
- Specify what it has to do if it does not know nothing about a concrete hostname or ip:
  something like
      r.parentresolver(none) --> if r does not know ip of one hostname, then there is no procedure for determining it
      r.parentresolver(ip) --> the parent DNS for resolv unknown hostnames

I know that all of that can do with resolv.rb but I don't know how.
Can you put me an example of how do it?

Thank you very much,
Xan.