ns1.impsat.net.co has no CNAME records.
Question and response
Question
dig ns1.impsat.net.co. NS
Answer
The response has no answer records.
Authority
impsat.net.co. 3122 SOA ns1.impsat.net.co. hostmaster.impsat.net.ar. 2230426014 10800 3600 604800 21600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0