  DNS is a basic Internet service which almost all other user services depend
on. However, what has been perceived in practice are a lot of inconsistencies
and errors in the configuration of servers that cause different problems. The
majority of such cases are included in this research with the aim of
identifying and classifying the major problems of DNS availability, performance
and security. In order to analyze these problems in correlation with DNS
administrators working practice, we have developed a methodology and tool for
testing, quantifying and analysis of DNS misconfigurations. The methodology and
tool were applied on three heterogeneous domain categories - the most popular
Internet domains, academic domains and one national top level domain. Our
results confirm relatively high percentage of misconfigured domains, especially
in the academic and national categories. However, we have shown that fixing the
configuration on relatively small number of name servers can have significant
impact to great number of domains. Proper domain management, permanent testing
and collaboration with other administrators are identified as measures to
improve domains operation, stability and security.
