When it comes to AL games, DCI numbers are only required if the character is played in a public location. If the character is exclusively played in home-based AL games, neither the player nor the DM requires a DCI number, but the characters still require logsheets tracking each and every session. If you play in a public location as part of the Encounters or Expeditions program however, you must have a DCI number for your character, and your public-play log entries must also include the DMs DCI number.