交换机是构成网络的基础设备，主要功能是负责网络通信数据包的交换传输。交换机根据功能变化分为五代，其中第二代交换机又称为以太网交换机，其工作于OSI（开放系统互连参考模型）的（ ）。
第二代交换机又称为以太网交换机，其工作于OSI（开放系统互连参考模型）的数据链路层。第二代交换机可以识别传输数据的MAC地址，并可选择端口进行数据转发。
Corporate decision makers require access to information from multiple such sources. Seting up queries on individual sources is both cumbersome and（ 71 ）. Moreover, the sources of data may store only current data, whereas decision makers may need access to（ 72 ）dataas well. A data warehouse is a repository（or archive）of information gathered from multiple sources, stored under a unified schema, at a（ 73 ）site. Once gathered, the data are stored for a long time, permitting access to historical data. Thus, data warehouses provide the user with a single consolidated（ 74 ）to data, making decision-support queries easier to write. Moreover, by accessing information for decision support from a data warehouse, the decision maker ensures that online transaction- processing systems are not（ 75 ）by the decision-supportworkdoad.
Corporate decision makers require access to information from multiple such sources. Seting up queries on individual sources is both cumbersome and（ 71 ）. Moreover, the sources of data may store only current data, whereas decision makers may need access to（ 72 ）dataas well. A data warehouse is a repository（or archive）of information gathered from multiple sources, stored under a unified schema, at a（ 73 ）site. Once gathered, the data are stored for a long time, permitting access to historical data. Thus, data warehouses provide the user with a single consolidated（ 74 ）to data, making decision-support queries easier to write. Moreover, by accessing information for decision support from a data warehouse, the decision maker ensures that online transaction- processing systems are not（ 75 ）by the decision-supportworkdoad.
Corporate decision makers require access to information from multiple such sources. Seting up queries on individual sources is both cumbersome and（ 71 ）. Moreover, the sources of data may store only current data, whereas decision makers may need access to（ 72 ）dataas well. A data warehouse is a repository（or archive）of information gathered from multiple sources, stored under a unified schema, at a（ 73 ）site. Once gathered, the data are stored for a long time, permitting access to historical data. Thus, data warehouses provide the user with a single consolidated（ 74 ）to data, making decision-support queries easier to write. Moreover, by accessing information for decision support from a data warehouse, the decision maker ensures that online transaction- processing systems are not（ 75 ）by the decision-supportworkdoad.
Corporate decision makers require access to information from multiple such sources. Seting up queries on individual sources is both cumbersome and（ 71 ）. Moreover, the sources of data may store only current data, whereas decision makers may need access to（ 72 ）dataas well. A data warehouse is a repository（or archive）of information gathered from multiple sources, stored under a unified schema, at a（ 73 ）site. Once gathered, the data are stored for a long time, permitting access to historical data. Thus, data warehouses provide the user with a single consolidated（ 74 ）to data, making decision-support queries easier to write. Moreover, by accessing information for decision support from a data warehouse, the decision maker ensures that online transaction- processing systems are not（ 75 ）by the decision-supportworkdoad.
Corporate decision makers require access to information from multiple such sources. Seting up queries on individual sources is both cumbersome and（ 71 ）. Moreover, the sources of data may store only current data, whereas decision makers may need access to（ 72 ）dataas well. A data warehouse is a repository（or archive）of information gathered from multiple sources, stored under a unified schema, at a（ 73 ）site. Once gathered, the data are stored for a long time, permitting access to historical data. Thus, data warehouses provide the user with a single consolidated（ 74 ）to data, making decision-support queries easier to write. Moreover, by accessing information for decision support from a data warehouse, the decision maker ensures that online transaction- processing systems are not（ 75 ）by the decision-supportworkdoad.
以下关于MapReduce技术的说法中，不正确的是（ ）。
相比于集中式数据库，分布式数据库具有（ ）的优点。
数据仓库是为了构建新的分析处理环境而出现的一种数据存储和组织技术，其特征不包括（ ）。
大数据的特性一般包括（ ）。
①数量大；②速度增长快；③多样性；④价值密度低。
由于机房断电，某个使用检查点记录的数据库出现故障，该故障属于（ ）。
