analyze mismatch causes

Even reproducible mismatches can have multiple causes:

• a bug in code under test
• non-compliant behavior on remote end (e.g. auhoritative servers)
• a network problem (like dumb firewall) on the way between test machine and remote end

Categorizing mismatches into these categories takes a lot of time and is tedious. We should use some automation for basic categorization. E.g. queries which are answered correctly according to DNSViz should be reported separately. We should store results from DNSViz and other tools for further analysis, like cluster analysis by detected problem. (Please note that DNSViz is just an example.)

This approach will certainly have multiple issues:

• Not all queries are suitable for analysis by DNSViz. This includes queries which test local resolver behavior but should not cause further communication with authoritative servers. E.g. queries with header bit RD=0.
• It does not discover firewall/network problems. Design needs to take into account these.