Kubernetes ACS 引擎：容器（pod）无法访问互联网

我正在使用 Kubernetes 集群，使用ACS-engine部署在 Azure 上。我的集群由 5 个节点组成。

• 1 个主 (unix VM) (v1.6.2)
• 2 unix 代理 (v1.6.2)
• 2 windows 代理 (v1.6.0-alpha.1.2959+451473d43a2072)

我创建了一个由以下 YAML 定义的unix pod：

Name:           ping-with-unix
Node:           k8s-linuxpool1-25103419-0/10.240.0.5
Start Time:     Fri, 30 Jun 2017 14:27:28 +0200
Status:         Running
IP:             10.244.2.6
Controllers:    <none>
Containers:
  ping-with-unix-2:
    Container ID:       
    Image:              willfarrell/ping
    Port:
    State:              Running
      Started:          Fri, 30 Jun 2017 14:27:29 +0200
    Ready:              True
    Restart Count:      0
    Environment:
      HOSTNAME: google.com
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-1nrh5 (ro)
Conditions:
  Type          Status
  Initialized   True
  Ready         True
  PodScheduled  True
Volumes:
  default-token-1nrh5:
    Type:       Secret (a volume populated by a Secret)
    SecretName: default-token-1nrh5
    Optional:   false
QoS Class:      BestEffort
Node-Selectors: beta.kubernetes.io/os=linux
Tolerations:    <none>
Events:         <none>

此 Pod 无法访问 Internet。

2017-06-30T12:27:29.512885000Z ping google.com every 300 sec
2017-06-30T12:27:29.521968000Z PING google.com (172.217.17.78): 56 data bytes
2017-06-30T12:27:39.698081000Z --- google.com ping statistics ---
2017-06-30T12:27:39.698305000Z 1 packets transmitted, 0 packets received, 100% packet loss

我创建了第二个 pod，目标是windows 容器，带有自定义 docker 图像。此图像实例化一个 HttpClient 并请求一个端点。它也没有互联网接入。我可以访问容器以运行交互式 PowerShell。我无法访问任何 DNS（由于无法访问互联网）。

PS C:\app> ping github.com
Ping request could not find host github.com. Please check the name and try again.
PS C:\app> ping 192.30.253.112

Pinging 192.30.253.112 with 32 bytes of data:
Request timed out.
Request timed out.

Ping statistics for 192.30.253.112:
    Packets: Sent = 2, Received = 0, Lost = 2 (100% loss),
Control-C

我必须配置什么才能允许我的容器访问互联网？
备注：我没有定义任何网络策略。