alertmh.imimobile.com has no NS records.
NS records for this zone are defined at imimobile.com.
NS records for this zone are defined at imimobile.com.
Question and response
Question
dig alertmh.imimobile.com. NS
Answer
The response has no answer records.
Authority
imimobile.com. 900 SOA ns-162.awsdns-20.com. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0