extdns06.na.sas.com has no CNAME records.
Question and response
Question
dig extdns06.na.sas.com. NS
Answer
The response has no answer records.
Authority
sas.com. 600 SOA dns3axxD0101nc0.net.sas.com. dnsadmin.sas.com. 2078292629 1800 300 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0