Each OSI network device is networked as shown in the figure. There are ______ ESs in the OSI network. (Host)

After executing the displaospf peer command on the MSR router RTA, the router output is as follows:

It can be judged from the above output that ________.

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 ______.

In the network shown in the figure, the adjacency relationship between the routers is established normally, and there is no configured route leakage. Then RTA will forward the IP packet whose destination is 16.224.3.20 to ________.

Regarding the Tpe4 LSA in the OSPF protocol, the correct statement is ______