Apex domains cannot have CNAME records.
Question and response
Question
dig d.c200.guam.net. NS
Answer
d.c200.guam.net. 5 NS ns2.guam.net.
d.c200.guam.net. 5 NS ns.guam.net.
Authority
The response has no authority records.
Additional
ns.guam.net. 5 A 202.128.7.1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0