First of all, there is nothing to "protect" you from. Snakes DO NOT ATTACK PEOPLE! Snakes only bite in self-defense when they themselves feel that they are threatened and under attack, so if you don't try to harm the snake, you won't be bitten.
Second, while nearly all dogs will go after a snake and try to kill it, recognizing the snake as prey/food(dogs are predators, after all), few dogs are able to kill a venomous snake, the only kind that is even remotely of any threat to humans, without suffering a bite themselves. A venomous snakebite in ANY dog is potentially lethal, and will cost you a LOT of money at the vet's to pull the dog through(I'm talking thousands of dollars here) and even still the dog could wind up with permanent scarring or loss of a limb. It is always a very good idea to teach a dog to AVOID or ignore snakes, since you're asking for trouble in encouraging a dog to go after them. Not only is it pointless, but it is also reckless and just plain stupid, like encouraging your dog to chase cars.
Second, while nearly all dogs will go after a snake and try to kill it, recognizing the snake as prey/food(dogs are predators, after all), few dogs are able to kill a venomous snake, the only kind that is even remotely of any threat to humans, without suffering a bite themselves. A venomous snakebite in ANY dog is potentially lethal, and will cost you a LOT of money at the vet's to pull the dog through(I'm talking thousands of dollars here) and even still the dog could wind up with permanent scarring or loss of a limb. It is always a very good idea to teach a dog to AVOID or ignore snakes, since you're asking for trouble in encouraging a dog to go after them. Not only is it pointless, but it is also reckless and just plain stupid, like encouraging your dog to chase cars.