www.sample.ivcert.net has no CNAME records.
Question and response
Question
dig www.sample.ivcert.net. NS
Answer
The response has no answer records.
Authority
ivcert.net. 897 SOA ns1.ivnosys.net. sistemas.ivnosys.com. 1770886836 7200 1800 1209600 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0