us02mx1.sigstr.com has no NS records.
NS records for this zone are defined at sigstr.com.
NS records for this zone are defined at sigstr.com.
Question and response
Question
dig us02mx1.sigstr.com. NS
Answer
The response has no answer records.
Authority
sigstr.com. 900 SOA ns-1703.awsdns-20.co.uk. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0