sip.cloudfinder.com has no NS records.
NS records for this zone are defined at cloudfinder.com.
NS records for this zone are defined at cloudfinder.com.
Question and response
Question
dig sipdir.online.lync.com. NS
Answer
The response has no answer records.
Authority
online.lync.com. 300 SOA ns1-33.azure-dns.com. azuredns-hostmaster.microsoft.com. 1 3600 300 2419200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0