多项选择题 Why do large OSPF networks use a hierarchical design?（）

单项选择题 A TCP/IP Transfer is diagrammed in the exhibit.A window size of three has been negotiated for this transfer. Which message will be returned from the receiver to the sender as part of this TCP/IP transfer?（）

多项选择题 Host1正在试图和Host2联系。RouterC的e0接口是down的，以下选项正确的是？（）