dn1relay2.mx.pearson.com has no NS records.
NS records for this zone are defined at pearson.com.
NS records for this zone are defined at pearson.com.
Question and response
Question
dig dn1relay2.mx.pearson.com. NS
Answer
The response has no answer records.
Authority
pearson.com. 900 SOA dns-amer-2.ptns.pearson.com. gns-dnsoperations.pearson.com. 2013052610 900 900 2592000 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0