ns1-39.azure-dns.com has no CNAME records.
Question and response
Question
dig ns1-39.azure-dns.com. NS
Answer
The response has no answer records.
Authority
azure-dns.com. 3334 SOA ns1-01.azure-dns.com. azuredns-hostmaster.microsoft.com. 6 7200 900 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0