_spf.colhost.com has no NS records.
NS records for this zone are defined at colhost.com.
NS records for this zone are defined at colhost.com.
Question and response
Question
dig _spf.colhost.com. NS
Answer
The response has no answer records.
Authority
colhost.com. 1800 SOA albert.ns.cloudflare.com. dns.cloudflare.com. 2396827034 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0