As shown, PC1 and PC2 are connected to RTC using ISATAP tunnel. In order to successfully establish a tunnel and PCI can automatically obtain a Pv6 address, what commands do administrators need to configure on the Tunnel0 interface of RTC?

Among the following statements about BGP load sharing, the correct one is ______.

H In the OSPF protocol, when the interface network type is NBMA (non-broadcast multiple access), the default Hello interval and neighbor failure time are respectively ______.

Level-1 routing exists in ________.

After the various routers in the figure establish IS-IS neighbor relationships and achieve synchronization, the routers that have sent CSNP messages are ______.