anchor.diff:  |The master proxies to node hosts via the Kubelet for `oc` commands.
   |===
   
  +[NOTE]
  +====
  +In the following table,
  +*(L)* indicates the marked port is also used in _loopback mode_,
  +enabling the master to communicate with itself.
  +
  +In a single-master cluster:
  +
  +- Ports marked with *(L)* must be open.
  +- Ports not marked with *(L)* need not be open.
  +
  +In a multiple-master cluster, all the listed ports must be open.
  +====
  +
   .Master to Master
   [cols='2,8']
   |===
  -| *53* or *8053*
  +| *53 (L)* or *8053* (L)
   |Required for DNS resolution of cluster services (SkyDNS).
   ifdef::openshift-origin[]
   Installations prior to 1.2 or environments upgraded to 1.2 use port 53.
  
positive.code: endif::[]
  New installations will use 8053 by default so that *dnsmasq* may be configured.
  
  | *2049*
  |Required when provisioning an NFS host as part of the installer.
  
  | *2379*
  
negative.code: |etcd requires this port be open between masters for leader election and peering
  connections when using standalone etcd (clustered).
  
  | *4001 (L)*
  |Used for embedded etcd (non-clustered) to accept changes in state.
  
  | *4789 (L)*
  |Required for SDN communication between pods on separate hosts.
  
  | *9000*
  