Perl related concepts are one category (including regular expressions, OO, cpan, etc.); you, apparently, need to prove that they are mastering them - perhaps, well performing the tasks of understanding, fixing and expanding the existing code (which, as I would interview the candidates, I was instructed to hire perl programmers).
perl , , . CGI, , , , HTTP . , , , : , , www.foobar.com . HTTP, TCP, IP, DNS, .. ..
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