Help with Caro Kann - 1.e4 c6 2.e5

Last night on chess.com my opponent played 2.e5 in the Caro Kann. I am new to this defense. Has anyone seen this move, and what do you think about it. Is it a mistake? 

After 1.e4 c6 2.e5 d5 3.d4, it can transpose into the advanced variation. The computer likes 2...d6, and both 2...d6 and 2...d5 have been played in about 10 master games. The move 2.e5 is extremely rare. I am guessing it is a mistake because Black can immediately challenge White’s e-pawn with ...d6, where as in the advanced variation, Black has to work around White’s e5 pawn, with moves like ...Bf5. Maybe that’s why the computer likes ...d6. 

Wow! Thanks for the explanation. Thinking about it some more, if White was trying to get me out of book, or try some tricky move order,  it still does not guarantee White one of the better lines in the Caro Kann, like the challenging Advanced Variation. If Black plays 2...d5, then White can play 3.d4, which transposes into the Advanced, and White is doing great. 

So the only and best move I see for Black to stop White from cramping Black is 2...d6, which stops the Advanced Variation, as after 3.d4 dxe5 4.dxe5 Qxd1+ 5.Kxd1 g6 6.Nf3 Bg7, White has lost castling rights and Black is exerting pressure on e5. Black is simply better. 

If White plays the computer’s top pick, 3.f4, then play gets very strange after 3...Bf5 4.Nf3 e6. I don’t know who is better in this computer line. The computer gives White a slight advantage. 

So, maybe 2...d5 is the best practical move for Black. If 3.exd6ep exd6 4.d4 d5, play looks straightforward for both sides, with both bishops having clear lines, but White has given up his e-pawn in the process. If 1.e4 c6 2.e5 d5 3.d4, Black is in familiar territory with the Advanced Variation.

With all that said, would you play 2...d5 or 2...d6. Those are the only moves played in master games. 

It seems that Ur opponent is trying to grab more space and cramp urs.Did he took on d4?

It seems that Ur opponent is trying to grab more space and cramp urs.Did he took on d4?

2...d6 looks quite good to me. 2..d5 isn't as good. If white takes en passant, you're good, but if he plays 3.d4 your just back in the Advance Variation

What about 4...c5?  after 1.e4 c6 2.e5 d6 3.f4 dxe5 4.fxe5 I know its taking 2 moves to get the pawn to c5 but white also took two moves to get his pawn to e5. Im thinking after 4..c5 white will have to worry about his e pawn becoming weak. Play might continue 5. c3(intending d4) 5...Nc6 .6. Nf3 Bg4 7. Bb5 Qd5 where maybe black can think about castling long or at least Rd8 at some point.

Just play 2...d5, there is not that much independent value to e5 (prob fewer than a similar idea in the french defense). and develop normally, Caro style bf5 e6 etc. If white doesnt do anything particularly threatening, get an early c5 going, the positions ends up looking like an improved french defense with the bad bishop" already outside the pawn chain.

2...d6 is ok, but you will need to learn a few lines of independent value which are not really better than 2...d5 and will just complicate your life. Instead of wasting memory slots on a very rarely seen sideline, just stick to your guns and play the Caro like a Caro.