t.Skip("IPv6 is required")
	}

	ipaddrs, err := DefaultResolver.LookupIPAddr(context.Background(), "fe80::1%lo0")
	if err != nil {
		t.Error(err)
	}
	for _, addr := range ipaddrs {
		if e, a := "lo0", addr.Zone; e != a {
			t.Errorf("wrong zone: want %q, got %q", e, a)
		}
	}

	addrs, err := DefaultResolver.LookupHost(context.Background(), "fe80::1%lo0")
	if err != nil {
		t.Error(err)

	if network == "" {
		return 0
	}
	n := network[len(network)-1]
	if n != '4' && n != '6' {
		n = 0
	}
	return n
}

// DefaultResolver is the resolver used by the package-level Lookup
// functions and by Dialers without a specified Resolver.
var DefaultResolver = &Resolver{}

// A Resolver looks up names and numbers.
//
// A nil *Resolver is equivalent to a zero Resolver.
type Resolver struct {

// It randomly fetches an IP via custom LookupHost function and dials it by the given dial
// function. LookupHost may implement an internal DNS caching implementation, lookupHost
// input if nil then net.DefaultResolver.LookupHost is used.
//
// It dials one by one and returns first connected `net.Conn`.
// If it fails to dial all IPs from cache it returns first error. If no baseDialFunc
// is given, it sets default dial function.
//

			return r, nil
		},
	}

	r := Resolver{PreferGo: true, Dial: fake.DialContext}
	// Change the default resolver to match our manipulated resolver
	originalDefault := DefaultResolver
	DefaultResolver = &r
	defer func() { DefaultResolver = originalDefault }()
	// Redirect host file lookups.
	defer func(orig string) { hostsFilePath = orig }(hostsFilePath)
	hostsFilePath = "testdata/hosts"

	tests := []struct {

// determine that value and use it in the "expected" results for the test
// cases in TestResolveAddr(). Need to wrap IPv6 addresses in square
// brackets.
func determineLocalHostIPString(t *testing.T) string {
	ips, err := net.DefaultResolver.LookupNetIP(context.Background(), "ip", "localhost")
	if err != nil || len(ips) == 0 {
		t.Fatalf("Test setup failure - unable to determine IP of localhost: %v", err)
	}
	var ret string
	for _, ip := range ips {

            ProjectDependencyResolver projectDependencyResolver,
            DependencyLockingProvider dependencyLockingProvider
        ) {
            DefaultConfigurationResolver defaultResolver = new DefaultConfigurationResolver(
                dependencyGraphResolver,
                repositoriesSupplier,
                metadataHandler,
                resolutionResultsStoreFactory,

	if err != nil {
		return nil, err
	}
	switch afnet {
	case "ip", "ip4", "ip6":
	default:
		return nil, UnknownNetworkError(network)
	}
	addrs, err := DefaultResolver.internetAddrList(context.Background(), afnet, address)
	if err != nil {
		return nil, err
	}
	return addrs.forResolve(network, address).(*IPAddr), nil
}

	if (len(lookupIPAddr) > 0) && (lookupIPAddr[0] != nil) {
		// if there are more than one lookup function, ignore all but first
		addrs, lookupErr = lookupIPAddr[0](ctx, host)
	} else {
		addrs, lookupErr = net.DefaultResolver.LookupNetIP(ctx, "ip", host)
	}
	if lookupErr != nil || len(addrs) == 0 {
		return "", fmt.Errorf("lookup failed for IP address: %w", lookupErr)
	}
	var resolvedAddr string

	for _, addr := range addrs {

	return &url.URL{Scheme: schemeReq, Host: net.JoinHostPort(info.Hostname, portReq)}, proxyTransport, nil
}

func isProxyableHostname(ctx context.Context, hostname string) error {
	resp, err := net.DefaultResolver.LookupIPAddr(ctx, hostname)
	if err != nil {
		return err
	}

	if len(resp) == 0 {
		return fmt.Errorf("no addresses for hostname")
	}
	for _, host := range resp {

			server := server
			var name string
			if def {
				name = "default/"
			} else {
				name = "go/"
			}
			t.Run(name+server, func(t *testing.T) {
				t.Parallel()
				r := DefaultResolver
				if !def {
					r = &Resolver{PreferGo: true}
				}
				fn(t, r, server)
			})
		}
	}
}

func TestNSLookupMX(t *testing.T) {
	testenv.MustHaveExternalNetwork(t)