This story in The Pioneer says

The IT Act 2000 has no explicit provisions to block websites, unless they promte pornography, slander, racism, gambling, terrorism or violence, which cannot be challenged under laws governing freedom of expression.

Can you imagine a government agency trying to block every one of the gambling sites on the web? (This is in a country where various states have their own lotteries!) But of course, like any Indian will tell you, in India, selective enforcement is not the exception: it is the rule. Laws are not made with enforceability in mind, they are made because they “look good on the books”.