A network connection is as follows:
HostA----GE0/0--MSR-1--S1/0---------S1/0--MSR-2--GE0/0----HostB
The customer requires that only ICMP messages between HostA and HostB are restricted. Which of the following is feasible? (multiple choice)

The customer's network connection looks like:
HostA----GE0/0--MSR-1--S1/0-----WAN----S1/0--MSR-2--GE0/0----HostB
The customer's WAN network only supports synchronization, so the S1/0 interface of the two routers can run ______. (Multiple choice)

The WAN links of the customer's two routers MSR-1 and MSR-2 use the PPP protocol. At the same time, MSR-1 is required as the main verifier to verify MSR-2 through PAP. Then what configuration is required on MSR-2?

In the switching network shown in the figure, all switches have enabled the STP protocol.

According to the information in the figure, which switch will be selected as the root bridge?

In the process of establishing a PPP session, when authentication is set and the authentication is passed, the PPP link enters the ______ phase.