Perhaps this question is best answered by discussing what you do not need to know: dates DOC/Gs were granted, percentages of grapes in the blend, production numbers, and food traditions.
Focus on what grapes are grown where, what DOC/Gs belong to what wine region, rivers, mountains and other topographical markers, climate types, soil types and unique grape growing or wine making attributes specific to each region.
Know your grapes! Spend some time working with the maps. Know where things are located. Know the champions (producers and people) of a particular DOC/G if mentioned.