* configure the factory when sample values impact the correctness of the test.
 */
class TestValueFactory : Closeable {
  var taskFaker: TaskFaker = TaskFaker()
  var taskRunner: TaskRunner = taskFaker.taskRunner
  var dns: Dns = Dns.SYSTEM
  var proxy: Proxy = Proxy.NO_PROXY
  var proxySelector: ProxySelector = RecordingProxySelector()
  var proxyAuthenticator: Authenticator = RecordingOkAuthenticator("password", null)

    return copy(writeTimeoutMillis = checkDuration("writeTimeout", timeout.toLong(), unit))
  }

  override fun withDns(dns: Dns): Interceptor.Chain {
    check(exchange == null) { "dns can't be adjusted in a network interceptor" }

    return copy(dns = dns)
  }

  override fun withSocketFactory(socketFactory: SocketFactory): Interceptor.Chain {

  @BeforeEach
  fun setUp() {
    socketFactory = SpecificHostSocketFactory(InetSocketAddress(server1.hostName, server1.port))

    client =
      clientTestRule
        .newClientBuilder()
        .dns(dns)
        .socketFactory(socketFactory)
        .eventListenerFactory(clientTestRule.wrap(eventRecorder))
        .build()
  }

  @RepeatedTest(100)
  fun http2OneBadHostOneGoodNoRetryOnConnectionFailure() {

    object DnsOverride : Override<Dns> {
      override fun Interceptor.Chain.value(): Dns = dns

      override fun Interceptor.Chain.withOverride(value: Dns): Interceptor.Chain = withDns(value)

      override fun OkHttpClient.Builder.withOverride(value: Dns): OkHttpClient.Builder = dns(value)

      override val nonDefaultValue: Dns = Dns { Dns.SYSTEM.lookup(it) }

...
01-01 12:53:32.811 10999 11089 D OkHttp  : [49 ms] responseHeadersEnd: Response{protocol=h2, code=200, message=, url=https://1.1.1.1/dns-query?dns=AAABAAABAAAAAAAAA3d3dwhmYWNlYm9vawNjb20AABwAAQ}
01-01 12:53:32.811 10999 11089 D OkHttp  : [49 ms] responseBodyStart
01-01 12:53:32.811 10999 11089 D OkHttp  : [49 ms] responseBodyEnd: byteCount=128

    val followRedirects: Boolean

    /**
     * Get the [DNS] instance for the OkHttpClient, or an override from the Call.Chain.
     */
    val dns: Dns

    /**
     * Override the [DNS] for the Call.Chain.
     *
     * @throws IllegalStateException if this is a Network Interceptor, since the override is too late.
     */
    fun withDns(dns: Dns): Chain

    /**

///

### DNS { #dns }

Now let's focus on all the actual HTTPS parts.

First, the browser would check with the **DNS servers** what is the **IP for the domain**, in this case, `someapp.example.com`.

The DNS servers would tell the browser to use some specific **IP address**. That would be the public IP address used by your server, that you configured in the DNS servers.

      }

    /**
     * Sets the DNS service used to lookup IP addresses for hostnames.
     *
     * If unset, the [system-wide default][Dns.SYSTEM] DNS will be used.
     */
    fun dns(dns: Dns) =
      apply {
        if (dns != this.dns) {
          this.routeDatabase = null
        }
        this.dns = dns
      }

    /**

        .newBuilder()
        .dns {
          Dns.SYSTEM.lookup("sni.cloudflaressl.com")
        }.build()

    val request =
      Request
        .Builder()
        .url("https://cloudflare-dns.com/cdn-cgi/trace")
        .build()
    client.newCall(request).execute().use { response ->
      assertThat(response.code).isEqualTo(200)
      assertThat(response.protocol).isEqualTo(Protocol.HTTP_2)

### 網域名稱 { #domain-name }

通常會先**取得**一個**網域名稱**，接著在 DNS 伺服器（可能是同一個雲端供應商）中設定它。

你可能會租一台雲端伺服器（虛擬機）或類似的服務，並擁有一個<dfn title="不會隨時間改變；非動態的">固定</dfn>的**公用 IP 位址**。

在 DNS 伺服器中，你會設定一個紀錄（「`A record`」）指向**你的網域**所對應的**伺服器公用 IP 位址**。

這通常在初次建置時設定一次即可。

/// tip

「網域名稱」是發生在 HTTPS 之前的事情，但一切都依賴網域與 IP 位址，因此在此一併說明。

///

### DNS { #dns }

現在聚焦在實際的 HTTPS 部分。

首先，瀏覽器會向 **DNS 伺服器**查詢該**網域的 IP**，例如 `someapp.example.com`。