> nslookup -type=mx flat8.co.jp
 Server:  ns10.vectant.ne.jp
 Address:  163.139.230.168
 
 Non-authoritative answer:
 flat8.co.jp     MX preference = 10, mail exchanger = mail.flat8.co.jp
 
 flat8.co.jp     nameserver = ns2.value-domain.com
 flat8.co.jp     nameserver = ns1.value-domain.com
 mail.flat8.co.jp        internet address = 174.143.151.33
 ns1.value-domain.com    internet address = 59.106.14.70
 ns2.value-domain.com    internet address = 202.229.187.26

googleのパブリックDNS（8.8.8.8）にflat8.co.jpのmxを聞きに行く。

 >nslookup -type=any flat8.co.jp 8.8.8.8
 Server:  google-public-dns-a.google.com
 Address:  8.8.8.8
 
 Non-authoritative answer:
 flat8.co.jp     MX preference = 10, mail exchanger = mail.flat8.co.jp
 flat8.co.jp
         primary name server = ns1.value-domain.com
         responsible mail addr = hostmaster.flat8.co.jp
         serial  = 1265677948
         refresh = 16384 (4 hours 33 mins 4 secs)
         retry   = 2048 (34 mins 8 secs)
         expire  = 1048576 (12 days 3 hours 16 mins 16 secs)
         default TTL = 2560 (42 mins 40 secs)
 flat8.co.jp     nameserver = ns1.value-domain.com
 flat8.co.jp     nameserver = ns2.value-domain.com