91.50.blue.net.gt has no CNAME records.
Question and response
Question
dig 91.50.blue.net.gt. NS
Answer
The response has no answer records.
Authority
blue.net.gt. 3029 SOA dns31.cloudns.net. abuse.blue.net.gt. 2025030903 7200 1800 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0