Which of the following descriptions about OSPFv3 are correct? (Multiple choice)
Correct Answer: A,B,C,D
Question 117
On the enterprise network shown in the figure, R3 is connected to the NMS, and all devices on the network communicate with the NMS through a VPN. During an inspection, it is found that R3 has redundant RTs (Route Targets). Which of the following commands can be run on R3 to delete the redundant RTs without affecting the connectivity between all devices and the NMS? Options:
Correct Answer: B,D
Comprehensive and Detailed In-Depth Explanation: 1. Understanding VPN Route Targets (RTs) in MPLS VPNs * Route Targets (RTs) define which VPN routes should be imported and exported among PE routers. * Import-extcommunity: Specifies which VPN routes should be accepted into a VRF. * Export-extcommunity: Specifies which VPN routes should be advertised from a VRF. * Correctly configuring RTs ensures proper route exchange between VPN sites. 2. Analyzing the RTs in the Diagram R3's Current Configuration: plaintext CopyEdit vpn-target 3:1 export-extcommunity vpn-target 3:2 export-extcommunity vpn-target 1:3 export-extcommunity vpn-target 1:3 import-extcommunity vpn-target 3:1 import-extcommunity vpn-target 3:2 import-extcommunity R1's Configuration: plaintext CopyEdit vpn-target 1:3 export-extcommunity vpn-target 3:1 import-extcommunity R2's Configuration: plaintext CopyEdit vpn-target 2:3 export-extcommunity vpn-target 3:2 import-extcommunity * R3 has redundant RTs because it both exports and imports unnecessary RTs. * We need to remove only redundant RTs without affecting NMS connectivity. 3. Evaluating Each Answer Choice A: "undo vpn-target 3:1 import-extcommunity" (# Incorrect) * R1 exports RT 1:3, and R3 imports it as 3:1. * Removing 3:1 import-extcommunity would block R3 from receiving routes from R1, disrupting connectivity to NMS. * Thus, this option is incorrect. B: "undo vpn-target 1:3 export-extcommunity" (# Correct) * R3 exports RT 1:3, but there is no need for R3 to advertise routes with 1:3. * R1 already exports 1:3, and R3 only needs to import it. * Removing vpn-target 1:3 export-extcommunity does not affect connectivity but eliminates redundancy. * # This is a correct choice. C: "undo vpn-target 1:3 import-extcommunity" (# Incorrect) * R3 needs to import 1:3 to receive routes from R1 (which is required for NMS communication). * If removed, R3 will not receive necessary routes, breaking connectivity. * Thus, this option is incorrect. D: "undo vpn-target 2:3 export-extcommunity" (# Correct) * R2 exports RT 2:3, but R3 does not need to receive it. * This RT is redundant and can be removed without affecting connectivity. * # This is a correct choice. 4. Evaluating the Answer Choices Option Correct? Reasoning A # Incorrect R3 must import 3:1 from R1 to maintain connectivity. B # Correct Removing export-extcommunity 1:3 eliminates redundancy without affecting connectivity. C # Incorrect Removing import-extcommunity 1:3 would block R3 from receiving necessary routes. D # Correct Removing export-extcommunity 2:3 eliminates redundancy without affecting connectivity. # Correct answer: B and D. Final Conclusion: * Route Targets (RTs) are used in MPLS VPNs to control route import/export policies. * R3 has redundant RTs, and removing unnecessary exports (1:3 and 2:3) optimizes configuration. * Correct commands to remove redundancy without affecting connectivity are: * # undo vpn-target 1:3 export-extcommunity * # undo vpn-target 2:3 export-extcommunity * Thus, the correct answer is: B and D.
Question 118
MPLS supports multi-layer label nesting. When the device receives an MPLS message, it will first process the label close to the second-layer header, that is, the MPLS label at the top of the stack.
Correct Answer: B
Question 119
As shown in the figure, the carrier BGP/MPLS IP VPN backbone network constructs SP through DP. If you want to realize the intercommunication between the two sites of user X through the BGP/MPLS IPVPN network, the 32bit mask of Loopback interface address must be used between PE1 and PE2 to establish the MP-IBGP peer relationship.
Correct Answer: B
Question 120
Configuring DHCP Snooping can be used to prevent imitators from attacking. Which of the following steps should be included in the configuration process? (Multiple choice)
