smtp02.nfon.net has no CNAME records.
Question and response
Question
dig smtp02.nfon.net. NS
Answer
The response has no answer records.
Authority
nfon.net. 2324 SOA ns4.nfon.net. hostmaster.nfon.net. 2026012701 3600 900 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0