No country, no matter it tries is immune to a malicious or war scenario cyber attack. One can prepare well. India is no exception.
The key is, that can its enemies which initiated the cyber attack withstand the retaliatory cyber attack, if India retaliates in kind.
If you get answer to the above then the net conclusion is that, unless you are suicidal, will not initiate the cyber attack. It's reverse impact is much greater on yourself than on the enemy.