Bill Huber at Scout.com says Randall in the lead for dime back job.

Randall has made a play or two at every practice to vault ahead of second-round pick Quinten Rollins, who had a strong offseason but missed the first three practices of training camp due to his hamstring. Randall has joined Shields, Hayward and Hyde in the dime.
http://www.scout.com/nfl/packers/story/1570733

Should also note Randall has played both outside spots. Rollins hasn't yet, he's been inside at slot CB.