Online shoe and clothing retailer Zappos has acknowledged a data breach in which information related to as many as 24 million customers was stolen. The retailer has taken assertive steps, including compelling customers to change passwords. Analysts and customers have a mixed reaction to the response, with some saying it’s “not a good idea” The attack is probably to gain information to sell to competitors on the black market, says Notre Dame professor John D’Arcy. Ponemon Institute estimates the cost of the data breach will probably be in the $5 billion range.”]