o1.mailer1.singtelmybusiness.com has no NS records.
NS records for this zone are defined at singtelmybusiness.com.
NS records for this zone are defined at singtelmybusiness.com.
Question and response
Question
dig o1.mailer1.singtelmybusiness.com. NS
Answer
The response has no answer records.
Authority
singtelmybusiness.com. 900 SOA ns-528.awsdns-02.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0