In the topology shown in the figure, the following configurations are performed on RTA, RTB, and RTC 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
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
If RTD can learn the route 10.0.0.0/24, how to configure it?

r Regarding the stub area in the OSPF protocol, which of the following statements is _______

The function of the OSPF Hello packet is _________.

As shown in the figure, PCA and PCB should communicate with each other, so _______ technology can be used between RTA and RTB.

M Execute the displaospf vlink command on the MSR router RTA, the router output is as follows:
$?OSPF Process 100 with Router ID 3.3.3.3
Virtual Links
Virtual-link Neighbor-ID -> 2.2.2.2 , Neighbor-State : Full
Interface: 20.0.0.1 (GigabitEthernet0/1)
Cost : 1 State : P-2-P Tpe : Virtual
Transit Area: 0.0.0.1
Timers : Hello 10 , Dead 40 , Retransmit 5 , Transmit Dela1
Judging from the above output _______.