_eblock1.vtr.com has no CNAME records.
Question and response
Question
dig _eblock1.vtr.com. NS
Answer
The response has no answer records.
Authority
vtr.com. 298 SOA ns00.vtr.net. hostmaster.vtr.net. 2025112002 10800 3600 604800 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0