As shown in the figure, the actual bandwidth of the Ethernet interface E1/0 of the MSR router is 10Mbps, and the actual link bandwidth of the serial port S2/0 is 64Kbps.

In order to preferentially use high-bandwidth links and achieve the purpose of route backup, which of the following solutions is the most reasonable?

In the topology shown in the figure, the following configurations are performed on RTA, RTB, RTC and RTD respectively:
RTA-LoopBack0] ip address 1.1.1.1 255.255.255.255
RTA]ospf 1
RTA-ospf-1]area 1
RTA-ospf-1-area-0.0.0.1]network 10.0.0.0 0.0.0.255
RTA-ospf-1]import-route direct
RTB-LoopBack0] ip address 2.2.2.2 255.255.255.255
RTB]ospf 1
RTB-ospf-1]area 1
RTB-ospf-1-area-0.0.0.1]network 10.0.0.0 0.0.0.255
RTB-ospf-1-area-0.0.0.1]area 0
RTB-ospf-1-area-0.0.0.0]network 2.2.2.2 0.0.0.0
RTB-ospf-1-area-0.0.0.0]network 20.0.0.0 0.0.0.255
RTC-LoopBack0] ip address 3.3.3.3 255.255.255.255
RTC]ospf 1
RTC-ospf-1]area 0
RTC-ospf-1-area-0.0.0.0]network 20.0.0.0 0.0.0.255
RTC-ospf-1-area-0.0.0.0]area 2
RTC-ospf-1-area-0.0.0.2]nssa default-route-advertise
RTC-ospf-1-area-0.0.0.2]network 30.0.0.0 0.0.0.255
RTC-ospf-1-area-0.0.0.2]network 3.3.3.3 0.0.0.0
RTD-LoopBack0] ip address 4.4.4.4 255.255.255.25
RTD]ospf 1
RTD-ospf-1]area 2
RTD-ospf-1-area-0.0.0.2]network 30.0.0.0 0.0.0.255
RTD-ospf-1-area-0.0.0.2]nssa
RTD-ospf-1]import-route direct
Which of the following routes may exist in the RTD routing table _______.

In the topology shown in the figure, the following configurations are performed on RTA, RTB, RTC and RTD respectively:
RTA] ospf 1 router-id 1.1.1.1
RTA-ospf-1] area 0
RTA-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
RTA-ospf-1-area-0.0.0.0] network 1.1.1.1 0.0.0.0
RTB] ospf 1 router-id 2.2.2.2
RTB-ospf-1] area 0
RTB-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
RTB-ospf-1-area-0.0.0.0] network 2.2.2.2 0.0.0.0
RTB-ospf-1] area 1
RTB-ospf-1-area-0.0.0.1] network 192.168.2.0 0.0.0.255
RTC] ospf 1 router-id 3.3.3.3
RTC-ospf-1] area 1
RTC-ospf-1-area-0.0.0.1] network 192.168.2.0 0.0.0.255
RTC-ospf-1] area 2
RTC-ospf-1-area-0.0.0.2] network 192.168.3.0 0.0.0.255
RTC-ospf-1-area-0.0.0.2] network 3.3.3.3 0.0.0.0
RTD] ospf 1 router-id 4.4.4.4
RTD-ospf-1] area 2
RTD-ospf-1-area-0.0.0.2] network 192.168.3.0 0.0.0.255
RTD-ospf-1-area-0.0.0.2] network 4.4.4.4 0.0.0.0
Then the routes that can be observed on RTD are _________

In the OSI network, Level-0 routing exists in _______.

Which of the following statements about PBR is correct is _________