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 {

    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) }

    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.

### 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`。

        override fun peek(): MockResponse = TODO()

        override fun shutdown() = TODO()
      }
  }

  @Test
  fun dns() {
    var dns: Dns = Dns { TODO() }

    val system: Dns = Dns.SYSTEM
  }

  @Test
  fun eventListener() {
    val eventListener =
      object : EventListener() {
        override fun callStart(call: Call) = TODO()

There may be many routes for a single address. For example, a webserver that is hosted in multiple datacenters may yield multiple IP addresses in its DNS response.

ドメイン名の話はHTTPSに関する話のはるか前にありますが、すべてがドメインとIPアドレスに依存するため、ここで言及する価値があります。

///

### DNS { #dns }

では、実際のHTTPSの部分に注目してみましょう。

まず、ブラウザは**DNSサーバー**に**ドメインに対するIP**が何であるかを確認します。今回は、`someapp.example.com`とします。

DNSサーバーは、ブラウザに特定の**IPアドレス**を使用するように指示します。このIPアドレスは、DNSサーバーで設定した、あなたのサーバーが使用するパブリックIPアドレスになります。

<img src="/img/deployment/https/https01.drawio.svg">

### TLS Handshake の開始 { #tls-handshake-start }

ブラウザはIPアドレスと**ポート443**（HTTPSポート）で通信します。

	public final fun setMaxRequestsPerHost (I)V
}

public abstract interface class okhttp3/Dns {
	public static final field Companion Lokhttp3/Dns$Companion;
	public static final field SYSTEM Lokhttp3/Dns;
	public abstract fun lookup (Ljava/lang/String;)Ljava/util/List;
}

public final class okhttp3/Dns$Companion {
}

public abstract class okhttp3/EventListener {

    assertFalse(InetAddresses.isInetAddress("016.016.016.016"));
  }

  public void testForStringIPv4Input() throws UnknownHostException {
    String ipStr = "192.168.0.1";
    // Shouldn't hit DNS, because it's an IP string literal.
    InetAddress ipv4Addr = InetAddress.getByName(ipStr);
    assertThat(InetAddresses.forString(ipStr)).isEqualTo(ipv4Addr);
    assertTrue(InetAddresses.isInetAddress(ipStr));
  }