Multithreaded perl script to enumerate DNS information
of a domain and discover non-contiguous IP blocks.

OPERATIONS:
 Get the host's address (A record).
 Get the nameservers (threaded).
 Get the MX record (threaded).
 Perform axfr queries on nameservers and
 get BIND VERSION (threaded).
 Get extra names and subdomains via google
 scraping (google query = "allinurl: -www site:domain").
 Brute force subdomains from file, can also
 perform recursion on subdomain that have NS records (all threaded).
 Calculate C class domain network ranges
 and perform whois queries on them (threaded).
 Perform reverse lookups on  netranges
 ( C class or/and whois netranges) (threaded).
 Write to domain_ips.txt file
 ip-blocks.