Apex domains cannot have CNAME records.
Apple
Domain verification
apple-domain-verification=NngSOWN35r2Fl1Sk
Facebook
Domain verification
facebook-domain-verification=s9yx10g1krm5frk7uz2onqbzs0adfr
Google
Domain verification
google-site-verification=26gqvOGxSzNyM-MI_jj0zgThDzv6Vxj3i7XapXP43uQ
Google
Domain verification
google-site-verification=MEIZzNcmic5DzCQzuHNWk6Dailv77wk3ggdpnvbdeY4
Google
Domain verification
google-site-verification=rfYpIn5MRAqeukrYfj6UqqI_GNJbp1AkGN21byTsyTY
Microsoft
Domain verification
MS=ms81439076
SwissSign
Domain verification
swisssign-check=Fd0iKT1QmUbIc9V9EqCLQOiHgnlRhBBv669B7EH8U8
Zone apex
Start of authority
Email
Serial
2014071141
Refresh
4h
Retry
45m
Expire
21d
Negative cache TTL
3h