In IS-IS, what is the difference between Hello messages on P2P type links and LAN type links?

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

In the IS-IS network as shown in the figure, RTA, RTC, RTD, and RTE establish a Level-2 adjacency relationship with each other; RTB establishes a Level-1 adjacency relationship with RTA, RTC. After the routing of each router is stable, when RTB accesses 192.168.14.1, it chooses the next hop as _________.
If RTA and RTC are added the following configuration at this time:
RTA-isis-1]import-route isis level-2 into level-1
RTC-isis-1]import-route isis level-2 into level-1
Then RTB selects the next hop as ________ when accessing 192.168.14.1.

In the topology shown in the figure, the following configurations are performed on RTA, RTB, RTC and RTD:
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 no-summarRTC-ospf-1-area-0.0.0.2]network
30.0.0.0 0.0.0.255
RTC-ospf-1]import-route direct
RTD-LoopBack0] ip address 4.4.4.4 255.255.255.255
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 process of generating the fast forwarding table, the quintuple refers to ________.