On the IS-IS network shown in the figure, R1 imports the default route using the default-route-advertise always level-1 command, and R2 imports the default route using the default- route-advertise always level-2 command.Which of the following routers have the default route in their routing tables? (Choose all that apply.)
Answer(s): A,B,C,D
In the given IS-IS network diagram:-R1 and R3 are Level-1 routers.-R2 is a Level-1-2 router, meaning it participates in both Level-1 and Level-2 routing.-R4 is a Level-2 router.Default Route Advertisement: 1. R1 advertises the default route in Level-1 using default-route-advertise always level-1. This means allLevel-1 routers in its area (R1, R3) will receive the default route. 2. R2 advertises the default route in Level-2 using default-route-advertise always level-2. This means all-Level-2 routers (R2, R4) will receive the default route.Default Route Presence: 1. R1 will have the default route because it originates the Level-1 default route. 2. R3 will have the default route because it is a Level-1 router in the same area as R1. 3. R2 will have the default route for both Level-1 (received from R1) and Level-2 (advertised itself). 4. R4 will have the default route because it is a Level-2 router receiving the default from R2.
On the OSPF network shown in the figure, area 1 is a common area, area 2 is a stub area, and area 3 is an NSSA. R5 imports an external route 10.0.5.5/32. Given this, which of the following routers does not have the route 10.0.5.5/32 in its routing table?
Answer(s): C
Understanding OSPF Route Propagation in the Given Network:-Area 0 (Backbone Area): Connects all other areas and allows all OSPF LSA types.-Area 1 (Common Area): A normal area that receives and propagates external routes.-Area 2 (Stub Area): Does not allow external Type 5 LSAs (external routes), but receives a default route from the ABR (R3).-Area 3 (NSSA - Not So Stubby Area): Allows external routes as Type 7 LSAs, which are later converted into Type 5 LSAs by the ABR (R1) and flooded into Area 0.Step-by-Step Route Propagation: 1. R5 Injects External Route (10.0.5.5/32)-Since Area 3 is an NSSA, external routes are advertised as Type 7 LSAs.R1 (ABR) converts Type 7 LSAs to Type 5 LSAs and injects them into Area 0. 2. R2 (Backbone Router) Receives the External RouteSince R2 is in Area 0, it receives Type 5 LSAs and learns 10.0.5.5/32. 3. R6 (Common Area) Receives the External Route-Area 1 is a normal area, meaning it accepts external Type 5 LSAs from Area 0.So, R6 learns the route 10.0.5.5/32. 4. R3 and R4 (Stub Area) Handling of External Routes-Stub areas do not allow Type 5 LSAs (external routes).-Instead, the ABR (R3) injects a default route (0.0.0.0) into Area 2, meaning R4 does not see 10.0.5.5/32 directly.-
The set-overload command is configured in the process of an IS-IS router. By default, how long after being restarted does the router exit the overload state?
Answer(s): B
The set-overload command in IS-IS is used to signal to other routers that the local router should not be used for transit traffic, typically during boot-up or maintenance. This helps prevent suboptimal routing decisions while the router is still initializing.
On the OSPF network shown in the figure, the cost values of links are marked. OSPF IP FRR is enabled on R1. The primary path from R1 to 10.0.3.3/32 is R1 -> R2 -> R3, and the backup path is R1 -> R4 -> R2 -> R3.
Understanding the Primary Path:-Destination: 10.0.3.3/32 (located on R3).Link Costs: - R1 → R2: Cost = 10 - R2 → R3: Cost = 5 - Total cost for the primary path (R1 → R2 → R3) = 10 + 5 = 15 (this is the lowest cost).Evaluating the Backup Path (R1 → R4 → R2 → R3):-Link Costs: - R1 → R4: Cost = 10 - R4 → R2: Cost = 20 - R2 → R3: Cost = 5 - Total cost for the backup path = 10 + 20 + 5 = 35Feasibility of OSPF IP FRR:-OSPF IP Fast Reroute (IP FRR) protects against link or node failures by precomputing a backup path that avoids the failed node/link.-A valid Loop-Free Alternate (LFA) must provide a backup path with a cost less than or equal to the primary path cost.-The primary path cost is 15, but the backup path has a total cost of 35, which is not a valid LFA because it does not meet the LFA criteria.The statement "The primary path from R1 to 10.0.3.3/32 is R1 → R2 → R3, and the backup path is R1 → R4 → R2 → R3" is FALSE because the backup path does not qualify as a valid IP FRR alternate.
On the OSPF network shown in the figure, areas 1, 2, and 3 are common areas. The IP address of Loopback0 on R5 is 10.0.5.5/32, and OSPF is enabled on the interface using the network command. ACL 2000 (with the matching rule shown in the figure) is configured on all routers. If the filter 2000 export command is run in area 0 (where R1, R2, and R3 reside), which of the following routers do not have the route 10.0.5.5/32 in their routing tables? (Choose all that apply.)
Answer(s): A,B
The filter 2000 export command is applied in Area 0, and the ACL configured with the rule deny source 10.0.5.5 0 will filter any routes originating from the IP address 10.0.5.5 (which is the Loopback0 address of R5) from being advertised in Area 0.Based on the provided network diagram:-R2 (Area 0): This router is in Area 0, so it will apply the export filter. R2 will not receive the route 10.0.5.5/32 because of the ACL 2000 export rule.-R3 (Area 0): This router is also in Area 0, so it will also be affected by the export filter. R3 will not receive the route 10.0.5.5/32.-R4 (Area 2): R4 is not in Area 0, so the filter does not affect it directly. R4 will still receive the route 10.0.5.5/32 from Area 1.-R6 (Area 1): Although R6 is in Area 1, it does not directly apply the export filter in Area 0. R6 will still send the route to R5, but R6 won't be directly impacted by the export filter.-
DRAG DROP (Drag and Drop is not supported)When a fault occurs on an OSPF network, traffic can be switched to another path only after several phases. Sort these phases in the correct sequence.Select and Place:
Answer(s): A
On the OSPF network shown in the figure, area 1 is an NSSA, area 2 is a common area, and R4 imports an external route 10.0.4.4/32. The router ID of each router is 10.0.X.X, where X is the number of the router. The asbr-summary 10.0.4.0 255.255.255.0 command is configured in the OSPF processes of R1 and R3. Which of the following statements is true?
Answer(s): A,B,C
The routing table of R3 contains the route 10.0.4.0/24. True: R3 is configured to summarize the external route from R4, so it will have 10.0.4.0/24 in its routing table.The routing table of R1 contains the route 10.0.4.0/24. True: Similarly, R1 is also configured to summarize the external route from R4, so it will have 10.0.4.0/24 in its routing table.The routing table of R3 does not contain the route 10.0.4.4/32. True: R3 will not have the specific route 10.0.4.4/32 because it only receives the summarized 10.0.4.0/24 route due to the asbr-summary configuration.The routing table of R2 contains the route 10.0.4.4/24. False: R2 is in Area 0, which does not receive external routes in the form of a /24. It would only receive the summarized version from R1 and R3, and it will not have 10.0.4.4/24.
On the OSPF network shown in the figure, the cost values of links are marked. OSPF IP FRR is enabled on R1, and the maximum load-balancing 8 command is configured in the OSPF process. If a service passes through the path R1 -> R5 -> R3 to reach 10.0.3.3/32, which of the following is the backup outbound interface for the service?
GE0/0/2 and GE0/0/3. R1 could potentially reroute using either GE0/0/2 or GE0/0/3, depending on the best available path.
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