pmi.nuffieldhealth.com has no NS records.
NS records for this zone are defined at nuffieldhealth.com.
NS records for this zone are defined at nuffieldhealth.com.
Question and response
Question
dig nuffield.eps.blinkm.co. NS
Answer
The response has no answer records.
Authority
blinkm.co. 3601 SOA dns1.registrar-servers.com. hostmaster.registrar-servers.com. 1772492282 43200 3600 604800 3601
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0