TheStreet's Jim Cramer said investors should steer clear of Joy Global (JOY) and do their research on Cisco (CSCO) if they're looking to buy shares of companies that play a part in the Internet of Things (IoT) sector. @SmcBmt asks whether he should add shares of Joy Global to his portfolio based on their dividend or if coal headwinds are too strong. Cramer said coal headwinds are too strong for investors to even consider initiating a position in the stock, much less the sector. @Vicdapirate asks what companies in the Internet of Things (IoT) sector might be good to add to his portfolio. Cramer said he believes Cisco is 'one of the most undervalued companies out there 'and investors who want to get in on IoT should look closely at adding it to their portfolios. @mi_jim asks Cramer's advice for Millennials and how he would advise them to invest. Cramer said Millennials should wait just a little longer for the S&P 500 to go down to 15 times earnings and then start buying. @fantasticsoccer said that he's about to retire and wants to put some of his cash into a large cap index fund and he wants to know whether he should put the money in all at once or a little at a time. Cramer said he should put a little money to work each week instead of buying all at once. If you have questions for Jim Cramer tweet him @JimCramer using #CramerQ.