spf1.comodo.com has no CNAME records.
Question and response
Question
dig spf1.comodo.com. NS
Answer
The response has no answer records.
Authority
comodo.com. 2051 SOA ns1.nurd.com. dnsadmin.nurd.com. 172800 60 60 60 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0