mail.eicra.com has no NS records.
NS records for this zone are defined at eicra.com.
NS records for this zone are defined at eicra.com.
Question and response
Question
dig mail.eicra.com. NS
Answer
The response has no answer records.
Authority
eicra.com. 1800 SOA elle.ns.cloudflare.com. dns.cloudflare.com. 2396729638 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0