The planet D'Qar is where the Resistance is located in the The Force Awakens.
The base was first strongly hinted at in the Star Wars novel, Lost Stars:
“We should list this planet as a potential base in the future. The Empire’s not interested, not much space lane traffic in this area, plus there’s plenty of water.
Here's the official description:
A lush world in the Outer Rim, D’Qar is the principal base of General Leia Organa’s Resistance. Rebel pilots first surveyed the planet before the Battle of Endor, and D’Qar housed a small Alliance outpost that went largely unused in the New Republic’s war with the Empire. The planet’s obscurity and lack of native intelligent life made it a perfect choice when General Organa’s new group needed a hidden base of operations.
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