DON-2N is quite specific radar. It's working with A-135 anti-ballistic missiles system and cover mostly the Moscow region. Don-2N is planning to be modernized.
Anyway, if you looking at early warning radar systems - the most recent one is "Voronezh-DM\VP"
All territory of Russia will be covered with this systems till 2020 Voronezh radar - Wikipedia, the free encyclopedia
Voronezh-DM in Armavir
Antenna
Blue: Systems which is were built during USSR time.
Black: Modern working systems