ns2.softlayer.net has no CNAME records.
Question and response
Question
dig ns2.softlayer.net. NS
Answer
The response has no answer records.
Authority
softlayer.net. 10753 SOA ns1.softlayer.com. root.softlayer.com. 2024110700 7200 600 1728000 43200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0