ns2.GOOGLE.com has no MX records.
Question and response
Question
dig ns2.GOOGLE.com. MX
Answer
The response has no answer records.
Authority
GOOGLE.com. 60 SOA ns1.GOOGLE.com. dns-admin.GOOGLE.com. 873285235 900 900 1800 60
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0