Apex domains cannot have CNAME records.
Question and response
Question
dig westmaster.com. NS
Answer
westmaster.com. 5 NS ns1.master.cz.
westmaster.com. 5 NS ns2.westmaster.com.
westmaster.com. 5 NS ns1.westmaster.com.
westmaster.com. 5 NS ns2.master.cz.
westmaster.com. 5 NS ns3.master.cz.
Authority
The response has no authority records.
Additional
ns1.westmaster.com. 5 A 81.31.37.17
ns2.westmaster.com. 5 A 80.79.16.3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0