On the network shown in the figure, IS-IS runs on R1, R2, R4, and R5, and the area ID is
49.0001. IS-IS runs on R3 and R6, and the area ID is 49.0002. The import-route isis level-2 into level-1 command is configured on R2.
In AS 65000, R1, R3, R4, and R6 each establish iBGP peer relationships with R2 and R5. R2 and R5 are Route Reflectors (RRs), and R1, R4, R3, and R6 are clients. An iBGP peer relationship is established between R2 and R5, and the same cluster ID is configured. The iBGP peer relationships are established using Loopback0. The IP address of Loopback0 on each router is
10.0.X.X/32, where X is the router number.
R1 and R4 import the external route 192.168.1.0/24 to BGP through the import-route command, and R3 and R6 import the external route 192.168.2.0/24 to BGP through the import-route command.

Which of the following statements are true?

In the IS-IS network shown in the figure, R1 introduces the default route through the "default- route-advertise always level-1" command. Which of the following descriptions are correct?
(Multiple choice)

The network administrator has deployed the IPSG function on the switch to prevent IP address spoofing attacks. Among the device interfaces shown in the figure, which interfaces will not perform IPSG checks after receiving packets? (Multiple choice)

In the OSPFv3 network shown in the figure, there are _______ Link-LSAs in R1's LSDB.

The MPLS label is a 20-bit identifier. When the administrator configures a static LSP, the label values of different IPLS devices cannot overlap.