1. Do weights assigned to servers only effect the balance within that particular backend?
2. When implementing weights for the first time, if I give all the servers in a backend the same number, would that be the same as before when there we no weights?
3. How do I calculate just how much traffic I am shiffting by adjust weights by certain amounts. For example:

    server web1 10.10.10.10 weight 100
    server web2 10.10.10.11 weight 100
    server web3 10.10.10.12 weight 90
    server web4 10.10.10.13 weight 90