Apex domains cannot have CNAME records.
Question and response
Question
dig iforex.com. NS
Answer
iforex.com. 2 NS pdns73.ultradns.net.
iforex.com. 2 NS pdns73.ultradns.org.
iforex.com. 2 NS pdns73.ultradns.com.
Authority
The response has no authority records.
Additional
pdns73.ultradns.net. 3 A 156.154.65.73
pdns73.ultradns.org. 3 A 156.154.67.73
pdns73.ultradns.net. 3 AAAA 2610:a1:1014:0:0:0:0:6d
pdns73.ultradns.org. 3 AAAA 2001:502:4612:0:0:0:0:6d
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0