透明代理教程中这个outbounds实在不明白，哪位朋友点解点解？

[qiangliu8183]

    {
        "tag": "dns-out",
        "protocol": "dns",
        "settings": {
            "address": "8.8.8.8"
        },
        "proxySettings": {
            "tag": "proxy"
        },
        "streamSettings": {
            "sockopt": {
                "mark": 2
            }
        }
    }

settings为什么加"address": "8.8.8.8"
proxySettings为什么加"tag": "proxy"