spf6.comodo.com has no NS records.
NS records for this zone are defined at comodo.com.
NS records for this zone are defined at comodo.com.
Question and response
Question
dig spf6.comodo.com. NS
Answer
The response has no answer records.
Authority
comodo.com. 2560 SOA ns1.nurd.com. dnsadmin.nurd.com. 172800 60 60 60 60
Additional
The response has no additional records.