Which statement is true, as relates to classful or classless routing?（）

Which IPsec security protocol should be used when confidentiality is required?（）

An employee of ABC company has move to an office on a different floor. Although the administrator is able to telnet to all of the routers,the address of Switch F is needed in order to verify that the employee remains in the same VLAN.Which action could be used by the administrator to find the IP address of Switch F?（）

Which cisco ios command can help to determine the timing of various debug events,relative to each other,when you are debugging a complicated router issue?（）

Three switches are connected to one anther via trunk ports.Assuming the default switch configuration,which switch is elected as the root bridge for the spanning-tree instance of vlan 1?（）

You have been asked to come up with a subnet mask that will allow all three web servers to be on the same network while providing the max number of subnets.Which network address and subnet mask meet this requirement?（）

Which statement describes the rule of split horizon?（）

A network administrator is planning a network installation for a large organization.The design requires 100 separate subnetworks,so the company has acquired a Class B network address.What subnet mask will provide the 100 subnetworks required, if 500 usable host addresses are required per subnet?（）

At which layer of the OSI model dose PPP perform?（）

Which command displays the CHAP authentication process as it occurs between two routers?（）