We've covered Google saying that they do not use domain registration length as a ranking factor before but it was back in 2009. We even discussed this topic a few times in the past and each time, we discussed it it came back up. In fact it didn't stop domain registrars from using this as a marketing tactic.
Read MoreBut again, John Mueller responds on Twitter about Matt Cutts saying they didn't and don't use this as a ranking factor saying that domain name registrars don't always share this information publicly, so they don't always know to use this as a ranking signal...