Apex domains cannot have CNAME records.
Question and response
Question
dig westcon.com. NS
Answer
westcon.com. 5 NS ns1.westcon.co.uk.
westcon.com. 5 NS ns1.westcon.com.
westcon.com. 5 NS ns3.westcon.com.
westcon.com. 5 NS ns2.westcon.com.
westcon.com. 5 NS ns4.westcon.com.
Authority
The response has no authority records.
Additional
ns1.westcon.com. 5 A 207.45.173.20
ns2.westcon.com. 5 A 216.150.156.51
ns3.westcon.com. 5 A 216.150.156.2
ns4.westcon.com. 5 A 207.45.173.10
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0