There are two types of requests in Ethereum - Call & Send
Send requests will send a transaction and hence will take up gas as transaction fee. Call requests will call the “constant” method and execute its smart contract method in the EVM without sending a transaction.
I have 2 questions here: 1. How can I connect to a main/testnet blockchain and make the read/call requests on that node? 2. If the above is possible, how does Ethereum protect itself from such attacks?