Example 3: Proxy Only Unresolved Hosts

This example works in an environment where internal DNS is set up so that it can resolve only internal host names, and the goal is to use a proxy only for hosts that aren’t resolvable:

    function FindProxyForURL(url, host)
    {
        if (isResolvable(host))
                return "DIRECT";
            else
                return "PROXY proxy.mydomain.com:8080";
    }

This example requires consulting the DNS every time, so it should be grouped with other rules so that DNS is consulted only if other rules do not yield a result:

    function FindProxyForURL(url, host)
    {
        if (isPlainhost name(host) ||
            dnsDomainIs(host, ".mydomain.com") ||
            isResolvable(host))
            return "DIRECT";
        else
            return "PROXY proxy.mydomain.com:8080";
    }