Clock start

Question
NCAA Football.  When a player runs out of bounds after making a first down the clock is stopped. The markers are moved and the ball is set for the next play. When should the clock start?  I have watched games where the clock resumes upon placement of the first down markers and ball but have also seen games where the clock does not start until the snap.  Which is correct?

Answer
Hal
As a simplistic answer: the NCAA timing rules provide for what you have described; When a player runs out of bounds after making a first down the clock is stopped  - the clock starts when ball is marked ready for play except in the last 2 minutes of the 2nd Qtr and 4th Qtr. (referred to as the 2 minute timing rules}

You note that  you have "watched games where the clock resumes upon placement of the first down markers [likely this is not in the last 2 minutes of a half].  You also note you have seen games where the clock does not start until the snap" [this is likely in the last 2 minutes of a half]