f5mgmt.ficolo.net has no CNAME records.
Question and response
Question
dig f5mgmt.ficolo.net. NS
Answer
The response has no answer records.
Authority
ficolo.net. 2982 SOA dns1.ficolo.net. hostmaster.ficolo.net. 2020091400 28800 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0