tax.ivcert.net has no NS records.
NS records for this zone are defined at ivcert.net.
NS records for this zone are defined at ivcert.net.
Question and response
Question
dig www.ivcert.net. NS
Answer
The response has no answer records.
Authority
ivcert.net. 1800 SOA ns1.ivnosys.net. sistemas.ivnosys.com. 1773656283 7200 1800 1209600 1800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0