Responsive Name Servers
Tests that the name servers for this domain respond to queries.
A domain name may have several name servers that can respond to queries for the IP address of the website. It is important that all of these name severs respond to queries, not just the one listed first. This test will check to make sure that each name server has a resolvable IP address. It will then query every name server to make sure that each one responds correctly and provides an answer.