When a machine is running a particular service, for example, a Web server, E-mail server, or peer-to-peer service, the machine must listen on a specific port.

当一台计算机正在运行某个特定的服务(例如，Web服务器、电子邮件服务器或者对等服务)时，该计算机必定会侦听某个特定的端口。

youdao

You need to have base machine images for the various roles (web server, E-mail server, database server, and so on) and to use tools like Chef or Puppet to automatically configure instances.

您需要有适用于各种角色(Web服务器、电子邮件服务器、数据库服务器等)的基础机器映像，并使用工具(如Chef或Puppet)来自动化配置实例。

youdao

You need to have base machine images for the various roles (web server, E-mail server, database server, and so on) and to use tools like Chef or Puppet to automatically configure instances.

您需要有适用于各种角色(Web服务器、电子邮件服务器、数据库服务器等)的基础机器映像，并使用工具(如Chef或Puppet)来自动化配置实例。

youdao