Example 3: Proxy Only Unresolved Hosts

This example works in an environment where internal DNS resolves only internal host names. 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. Therefore, you would group this example 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";
    }