c1.bitrix24.com has no NS records.
NS records for this zone are defined at bitrix24.com.
NS records for this zone are defined at bitrix24.com.
Question and response
Question
dig ec2-23-21-90-7.compute-1.amazonaws.com. NS
Answer
The response has no answer records.
Authority
compute-1.amazonaws.com. 60 SOA ns-943.awsdns-53.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 60
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0