mail01.learn.pearson.com has no NS records.
NS records for this zone are defined at learn.pearson.com.
NS records for this zone are defined at learn.pearson.com.
Question and response
Question
dig mail01.learn.pearson.com. NS
Answer
The response has no answer records.
Authority
learn.pearson.com. 900 SOA dns-amer-2.ptns.pearson.com. gns-dnsoperations.pearson.com. 75 900 900 2592000 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0