Apex domains cannot have CNAME records.
Question and response
Question
dig solarwinds.com. NS
Answer
solarwinds.com. 5 NS a13-66.akam.net.
solarwinds.com. 5 NS a4-65.akam.net.
solarwinds.com. 5 NS a28-64.akam.net.
solarwinds.com. 5 NS a9-66.akam.net.
solarwinds.com. 5 NS a1-139.akam.net.
solarwinds.com. 5 NS a26-67.akam.net.
Authority
The response has no authority records.
Additional
a4-65.akam.net. 1 A 72.246.46.65
a9-66.akam.net. 1 A 184.85.248.66
a1-139.akam.net. 1 A 193.108.91.139
a13-66.akam.net. 1 A 2.22.230.66
a26-67.akam.net. 1 A 23.74.25.67
a28-64.akam.net. 1 A 95.100.173.64
a4-65.akam.net. 1 AAAA 2600:1480:9000:0:0:0:0:41
a9-66.akam.net. 1 AAAA 2a02:26f0:117:0:0:0:0:42
a1-139.akam.net. 1 AAAA 2600:1401:2:0:0:0:0:8b
a13-66.akam.net. 1 AAAA 2600:1480:800:0:0:0:0:42
a26-67.akam.net. 1 AAAA 2600:1480:b800:0:0:0:0:43
a28-64.akam.net. 1 AAAA 2600:1480:d800:0:0:0:0:40
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0