code: def lookup(self, ip_address):
          
  
          # Is this already in our cache
          if self.ip_lookup_cache.get(ip_address):
              domain = self.ip_lookup_cache.get(ip_address)
  
          # Is the ip_address local or special
          elif not self.lookup_internal and net_utils.is_internal(ip_address):
              domain = 'internal'
          elif net_utils.is_special(ip_address):
              domain = net_utils.is_special(ip_address)
  
          # Look it up at this point
          else:
              domain = self._reverse_dns_lookup(ip_address)
  
          # Cache it
          self.ip_lookup_cache.set(ip_address, domain)
  
          # Return the domain
          return domain
docs: Try to do a reverse dns lookup on the given ip_address