ec2-98-87-170-74.compute-1.amazonaws.com has no CNAME records.
Question and response
Question
dig ec2-98-87-170-74.compute-1.amazonaws.com. NS
Answer
The response has no answer records.
Authority
compute-1.amazonaws.com. 58 SOA ns-943.awsdns-53.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0