The API changes should provide both source and binary  （71）for programs written to the original API.That is,existing program binaries should continue to operate when run on a system supporting the new API.In addition,existing  （72）that are re-compiled and run on a system supporting the new API should continue to operate.Simply put,the API  （73）for multicast receivers that specify source filters should not break existing programs.The changes to the API should be as small as possible in order to simplity the task of converting existing  （74）receiver applications to use source filters.Applications should be able to detele when the new  （75）filter APIs are unavailable(e.g., calls fail with the ENOTSUPP erroe) and react gracefully(e.g., revert to old non-source-filter API or display a meaningful error message to the user).

71.

75.(          )

74.(         )

73.(    )

72.(   )

在STP生成树中，断开的链路并不是随意选择的，而是通过设备、接口、链路优先级等决定的。在下图所示的连接方式中，哪条链路是作为逻辑链路断开而备份使用的？ （70）　。

The API changes should provide both source and binary  （71）for programs written to the original API.That is,existing program binaries should continue to operate when run on a system supporting the new API.In addition,existing  （72）that are re-compiled and run on a system supporting the new API should continue to operate.Simply put,the API  （73）for multicast receivers that specify source filters should not break existing programs.The changes to the API should be as small as possible in order to simplity the task of converting existing  （74）receiver applications to use source filters.Applications should be able to detele when the new  （75）filter APIs are unavailable(e.g., calls fail with the ENOTSUPP erroe) and react gracefully(e.g., revert to old non-source-filter API or display a meaningful error message to the user).

71.

69.

光缆布线工程结束后进行测试是工程验收的关键环节。以下指标中不属于光缆系统的测试指标的是 （67）　。

如图所示网络结构，当Swith1和Swith2都采用默认配置，那么PC2和PC4之间不能通信，其最可能的原因是 （68）　。如果要解决此问题，最快捷的解决方法是 （69）　。

在网络数据传输过程中都是收、发双向进行的。一般来说，对于光纤介质也就需要两条光纤分别负责数据的发送和接收。近年来已经有了在单条光纤上同时传输收发数据的技术，下面支持单条光纤上同时传输收发数据的技术是 （66）　。