You can also set the following environment variables before running the cpan shell, which will avoid all questions, whether by the cpan shell or by modules you are installing

export PERL_MM_USE_DEFAULT=1
export PERL_EXTUTILS_AUTOINSTALL="--defaultdeps"

perl -MCPAN -e 'install Bundle::CPAN'
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You may be interested in App::cpanminus the new zero configuration CPAN client