a.web.mkc1.etrn.com has no CNAME records.
Question and response
Question
dig a.web.mkc1.etrn.com. NS
Answer
The response has no answer records.
Authority
etrn.com. 2560 SOA ns1.chi1.etrn.com. hostmaster.etrn.com. 1771894443 16384 2048 1048576 2560
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0