Ruby/Network/DNS

require "resolv"
dns = Resolv::DNS.new
domain = "oreilly.ru"
dns.each_resource(domain, Resolv::DNS::Resource::IN::MX) do |mail_server|
  puts mail_server.exchange
end
# smtp1.oreilly.ru
# smtp2.oreilly.ru
==
Get name server
require "resolv"
dns = Resolv::DNS.new
dns.each_resource(domain, Resolv::DNS::Resource::IN::NS) do |nameserver|
  puts nameserver.name
end
# a.auth-ns.sonic.net
# b.auth-ns.sonic.net
# c.auth-ns.sonic.net
# ns.oreilly.ru

require "resolv"
Resolv::DNS.new.each_address("oreilly.ru") { |addr| puts addr }