a.adobe.com has no CNAME records.
Question and response
Question
dig a.adobe.com. NS
Answer
The response has no answer records.
Authority
adobe.com. 147 SOA exfer-vip-01.corp.adobe.com. hostmaster.adobe.com. 11332 1800 600 2419200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0