1. gmail.com

Understanding Gmail Domains: gmail.com, googlemail.com, and google.com

By Ajay Goel in gmail Interesting

https://www.gmass.co/blog/domains-gmail-com-googlemail-com-and-google-com/

http://support.google.com/a/bin/answer.py?hl=en&answer=33786

%dnsqr mx gmail.com

15 gmail.com:
150 bytes, 1+5+0+0 records, response, noerror
query: 15 gmail.com
answer: gmail.com 3600 MX 30 alt3.gmail-smtp-in.l.google.com
answer: gmail.com 3600 MX 5 gmail-smtp-in.l.google.com
answer: gmail.com 3600 MX 40 alt4.gmail-smtp-in.l.google.com
answer: gmail.com 3600 MX 10 alt1.gmail-smtp-in.l.google.com
answer: gmail.com 3600 MX 20 alt2.gmail-smtp-in.l.google.com

14:30f%dnsqr aaaa gmail-smtp-in.l.google.com ~

28 gmail-smtp-in.l.google.com:
72 bytes, 1+1+0+0 records, response, noerror
query: 28 gmail-smtp-in.l.google.com
answer: gmail-smtp-in.l.google.com 300 28 &\007\370\260@\016\014\001\000\000\000\000\000\000\000\032

14:31f%dnsqr a gmail-smtp-in.l.google.com ~

1 gmail-smtp-in.l.google.com:
60 bytes, 1+1+0+0 records, response, noerror
query: 1 gmail-smtp-in.l.google.com
answer: gmail-smtp-in.l.google.com 300 A 74.125.129.27