sisc-tor-web02.sisc.com has no CNAME records.
Question and response
Question
dig sisc-tor-web02.sisc.com. NS
Answer
The response has no answer records.
Authority
sisc.com. 1315 SOA kirk.ns.cloudflare.com. dns.cloudflare.com. 2397725882 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0