use Date::Calc qw( check_date );

while ( <DATA> )
{
    chomp;
    my @date = ( /(\d+)/g )[2,0,1];
    print and print check_date(@date) ? "-->Yep\n" : "-->Nope\n";
}

__END__
1.1.1
6/4/1989
2-29-2000
2/29/2001