In the topology shown in the figure, the RTC, RTD, and RTE are configured as follows:
RTC]ospf 1 router-id 2.2.2.2
RTC-ospf-1]area 2
rtc-ospf-1-area-0.0.0.2]nssa
rtc-ospf-1-area-0.0.0.2]network 30.0.0.0 0.0.0.255
RTD]ospf 1 router-id 1.1.1.1
RTD-ospf-1]area 2
RTD-ospf-1-area-0.0.0.2]network 40.0.0.0 0.0.0.255
RTE-LoopBack0] ip address 5.5.5.5 255.255.255.255
RTE]ospf 1
RTE-ospf-1]area 2
RTE-ospf-1-area-0.0.0.2]network 30.0.0.0 0.0.0.255
RTE-ospf-1-area-0.0.0.2]network 40.0.0.0 0.0.0.255
RTE-ospf-1-area-0.0.0.2]nssa
RTE-ospf-1]import-route direct
but_________ .

In the topology shown in the figure, execute the following command on the RTA:
RTA-ospf-1] default-route-advertise
The default route cannot be observed in the routing table of the RTC router, the impossible reason is ______

In the topology shown in the figure, the following configurations are performed on RTA and RTB respectively
RTA-ospf-1-area-0.0.0.1] network 192.168.0.0 0.0.0.255
RTA-ospf-1-area-0.0.0.1] network 192.168.1.0 0.0.0.255
RTA-ospf-1-area-0.0.0.1] network 192.168.2.0 0.0.0.255
RTA-ospf-1-area-0.0.0.1] network 192.168.3.0 0.0.0.255
RTA-ospf-1-area-0.0.0.1] network 192.168.4.0 0.0.0.255
Now it is required that the RTC cannot learn the routes configured in the above RTA. What configurations can be performed on the router?

In the network shown in the figure, the BGP route learning among the routers is normal, and the BGP route attributes all take the default values.
After the route 9.0.0.0 is imported into BGP on RTD, if the next hop of route 9.0.0.0 on RTA is to point to RTC, the following adjustment methods are feasible: ______

In the topology shown in the figure, the following configurations are performed on RTA , RTB , RTC and RTD respectively

then no injection into zone 2