RTA and RTB run OSPF routing protocol, and both belong to the backbone area.
Which of the following methods can be used to advertise the RTA direct route 192.168.1.0/24 to the OSPF routing domain?

In the topology shown in the figure, the following configurations are performed on RTA, RTB, and RTC:
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
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 20.0.0.0 0.0.0.255
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]stub
RTC-ospf-1-area-0.0.0.2]network 30.0.0.0 0.0.0.255
How to configure if RTD can learn route 10.0.0.0/24?

As shown in the figure, RTA is the border router of OSPF routing domain and BGP routing domain. If a BGP route with a MED value of 200 is imported into OSPF on RTA, the COST value of the route learned by RTB is ______ by default.

In the topology shown in the figure, the following configurations are performed on RTA and RTB respectively:
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
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 20.0.0.0 0.0.0.255
If area 2 needs to be configured as a TotalStub area, how should it be configured on RTC and RTD?

Regarding the default metric values ​​for route import by different routing protocols, which of the following descriptions is __________