See: http://www.dnsinspect.com/digicert.com/1421684164 - Fail Identical NS records.
Look for IDS alerts here: http://urlquery.net/report.php?id=1421682479040
On stealth name servers and errors: https://support.dnsmadeeasy.com/index.php?/Knowledgebase/Article/View/108/16/why-am-i-getting-these-stealth-name-server-errors-and-warnings
Missing nameservers and spam reported: http://knujon.com/nameservers/NS1.P03.DYNECT.NET.html
polonus