spf2.web.com has no NS records.
NS records for this zone are defined at web.com.
NS records for this zone are defined at web.com.
Question and response
Question
dig spf2.web.com. NS
Answer
The response has no answer records.
Authority
web.com. 1800 SOA ian.ns.cloudflare.com. dns.cloudflare.com. 2397067387 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0