1,001 CCNA Questions: Chapter 19 Router Essentials and Route Summarization

C. Administrative distance of 120 D. Is classless RIPv2 is a classless routing protocol (support VLSM) and has an administrative distance of 120.

Which of the following is true of RIPv2? (Select two.) (A) Administrative distance of 90 (B) Is classful (C) Administrative distance of 120 (D) Is classless (E) Vendor specific

B. 172.16.0.0/21 If you were to write out the binary of the relevant portions of the network IDs, you would get the figure below. To create a summary route, you simply identify the network bits that are the same for each of those networks (8+8+5=21).

You are configuring OSPF and need to determine the summary route for networks 172.16.0.0 up to 172.16.7.0. Which of the following identifies the summary route? (A) 172.16.0.0/20 (B) 172.16.0.0/21 (C) 172.16.0.0/22 (D) 172.16.0.0/23

B. The EIGRP route The route with the lowest administrative distance would be selected in this case. RIP has an administrative distance of 120, OSPF has an administrative distance of 110, and EIGRP has an administrative distance of 90.

You have no static routes configured on the router. A router learns about a route to the same network from OSPF, EIGRP, and RIP. Which route is added to the routing table? (A) The RIP route (B) The EIGRP route (C) The OSPF route (D) All the routes

A. Topology table C. Neighbor table E. Routing table Link state routing tables use a topology table identifying the entire network topology, a neighbor table identifying neighboring routers, and a routing table which includes the current routes.

What are the three tables that a link state routing protocol typically uses? (Select three.) (A) Topology table (B) MAC table (C) Neighbor table (D) STP table (E) Routing table

C. 110 OSPF has an administrative distance of 110.

What is the administrative distance of OSPF? (A) 90 (B) 100 (C) 110 (D) 120 (E) 1

D. 120 RIP has an administrative distance (AD) of 120.

What is the administrative distance of RIP? (A) 90 (B) 100 (C) 110 (D) 120 (E) 1

E. 1 A static route has an administrative distance of 1.

What is the default administrative distance of a static route? (A) 90 (B) 100 (C) 110 (D) 120 (E) 1

D. To reduce the size of the routing table The goal of route summarization is to reduce the size of the routing table by not listing each different route — you can use route summarization to summarize multiple routes as one.

What is the goal of route summarization? (A) To support different size subnets (B) To share routing table information other routers (C) To prevent loops on the network (D) To reduce the size of the routing table

B. Is classful C. Administrative distance of 120 RIPv1 is a classful protocol, which has an administrative distance of 120. Being classful means that the protocol does not send subnet mask information with the route table.

Which of the following are true of RIPv1? (Select two.) (A) Administrative distance of 90 (B) Is classful (C) Administrative distance of 120 (D) Is classless (E) Vendor specific

A. Holddown timer The holddown timer is a feature on a router that forces it to retain routing information for a short period of time even after receiving a routing update with conflicting information. Once a route is marked unreachable, the route is held for the duration of the timer before accepting a new route to the destination.

Which of the following causes a router to ignore updates from lower metric paths for a period of time? (A) Holddown timer (B) Poison reverse (C) Count to infinity (D) LSA (E) Split horizon

D. ip route 21.0.0.0 255.0.0.0 20.0.0.2 110 In order to add a static route you use the ip route command followed by the route you are adding, subnet mask, and the next hop. By default the administrative distance would be set to 1 so if you want to change it you set the new administrative distance value at the end of the command (such as the 110). You may want to do this so that the static route acts as a backup to a route learned via a routing protocol.

Which of the following commands alters the administrative distance on the static route from the default value? (A) ip route 21.0.0.0 255.0.0.0 20.0.0.2 (B) ip route 21.0.0.0 255.0.0.0 20.0.0.2 admin-distance 110 (C) admin-distance static route 21.0.0.0 255.0.0.0 20.0.0.2 110 (D) ip route 21.0.0.0 255.0.0.0 20.0.0.2 110

B. Hello messages E. LSA from other routers A link state routing protocol uses hello messages that it sends out to each of its interfaces to discover neighboring routers. The LSA messages are used to announce changes in the network topology.

Which of the following does a link state routing protocol use to build the topology database? (Select two.) (A) Hop count (B) Hello messages (C) Static routes (D) BPDU from other devices (E) LSA from other routers

A. More secure because the administrator must add the routes D. No bandwidth is being used to update the routing tables. The huge benefit to static routing is that you are not using any network bandwidth to have routing protocols update the routing tables of other routers. Also, static routing is more secure because the administrator must manually add the route versus the router just adding what it hears from others (as is the case with dynamic routing protocols).

Which of the following identifies the benefit of static routing over dynamic routing? (Select two.) (A) More secure because the administrator must add the routes. (B) Less secure because the administrator must add the routes. (C) Bandwidth is being used to update the routing tables. (D) No bandwidth is being used to update the routing tables.

C. 10.4.0.0/14 If you were to write out the binary of the relevant portions of the network IDs, you would get the figure below. To create a summary route, you simply identify the network bits that are the same for each of those networks (8+6=14).

Which of the following identifies the summary route for networks 10.4.0.0 up to 10.7.0.0? (A) 10.0.0.0/14 (B) 10.0.0.0/15 (C) 10.4.0.0/14 (D) 10.4.0.0/13

B. 120.12.0.0/14 If you were to write out the binary of the relevant portions of the network IDs, you would get the figure below. To create a summary route, you simply identify the network bits that are the same for each of those networks (8+6=14).

Which of the following identifies the summary route for networks 120.12.0.0 to 12.15.0.0? (A) 120.12.0.0/16 (B) 120.12.0.0/14 (C) 120.12.0.0/23 (D) 120.12.0.0/13

B. Poison reverse Poison reverse is a routing feature to help reduce routing loops by a router sending an update back to its neighbor for a downed route with an infinite metric.

Which of the following involves a router learning that a route is down from its neighbor, and then sending an update back to the neighbor on the route with an infinite metric? (A) Holddown timer (B) Poison reverse (C) Count to infinity (D) LSA (E) Split horizon

A. It decreases convergence time by sending out an update as soon as there is a change to the network topology. Triggered updates are a feature of link state routing protocols and they send out notification immediately when there is a change in the network topology.

Which of the following is a benefit of triggered updates? (A) It decreases convergence time by sending out an update as soon as there is a change to the network topology. (B) They are more accurate than scheduled updates. (C) They are supported by all routing protocols. (D) It increases convergence time by sending out an update as soon as there is a change to the network topology.

D. LSA When a change occurs to the network topology, a router sends out LSA messages informing other routers on the network of the change. This causes the routers to recalculate routes and update their topology databases.

Which of the following is the term for packets that are flooded when a topology change occurs? (A) Holddown timer (B) Poison reverse (C) Count to infinity (D) LSA (E) Split horizon

E. Split horizon Split horizon is a feature to help prevent routing loops by preventing a router from sending knowledge of a route out the interface it received knowledge of the route through.

Which of the following is the term for preventing a router from sending updates on a route through the interface on which it received the knowledge of the route? (A) Holddown timer (B) Poison reverse (C) Count to infinity (D) LSA (E) Split horizon

B. Is vendor-specific E. Administrative distance of 90 EIGRP is a Cisco-specific routing protocol, so it could only be used on networks supporting Cisco devices, and has an administrative distance of 90.

Which of the following is true of EIGRP? (Select two.) (A) Uses cost as its metric (B) Is vendor-specific (C) Is an open standard (D) Administrative distance of 110 (E) Administrative distance of 90

A. Elects a DR D. Uses cost as its metric OSPF elects a designated router (DR) that other routers on the OSPF network will exchange routing information with. Also, to calculate the best pathway, OSPF uses cost instead of hop count, as is the case with RIP.

Which of the following is true of OSPF? (Select two.) (A) Elects a DR (B) Is vendor-specific (C) Administrative distance of 90 (D) Uses cost as its metric (E) Administrative distance of 110

D. They do not send the subnet mask info with the routing update. Classful routing protocols do not send the subnet mask information with the routing update, so therefore do not support VLSM; they assume the same subnet mask is used on each network.

Which of the following is true of classful routing protocols? (A) They send subnet mask info with the routing update. (B) They use wildcard masks. (C) They use the route with the highest cost pathway. (D) They do not send the subnet mask info with the routing update.

B. They use more resources as they store multiple tables in memory D. Use triggered updates to reduce the time to converge Link state routing protocols use more resources as they store multiple tables in memory to track the network topology. Link state routing protocols also use triggered updates to notify other routers of a change in the network topology.

Which of the following is true of link state routing protocols? (Select two.) (A) Choose the route with the lowest hop count (B) They use more resources as they store multiple tables in memory (C) Use a single table to share routing information (D) Use triggered updates to reduce the time to converge

B. EIGRP EIGRP is a Cisco proprietary routing protocol. If you have a network with routers from different vendors, you will need to use an industry standard routing protocol such as RIP or OSPF.

Which of the following routing protocols are vendor specific? (A) RIP (B) EIGRP (C) OSPF (D) ARP

B. OSPF OSPF is the only routing protocol that does not auto summarize routes; you must manually summarize the routes to take advantage of route summarization.

Which of the following routing protocols does not auto summarize routes? (A) RIP (B) OSPF (C) EIGRP (D) IGRP

A. SW1(config-if)#switchport mode trunk The port on the switch that is connected to the router on the stick will need to be configured as a trunk port so that it can carry traffic for all VLANs to the router.

Which of the following switch commands would you use on the port that is connected to a router on a stick? (A) SW1(config-if)#switchport mode trunk (B) SW1(config-if)#switchport mode access (C) SW1(config-if)#switchport mode sub-interface (D) SW1(config-if)#switchport port-security

D. 131.107.16.0/22 If you were to write out the binary of the relevant portions of the network IDs, you would get the figure below. To create a summary route, you simply identify the network bits that are the same for each of those networks, in this case, 8+8+6=22 bits

You are configuring OSPF and need to determine the summary route for networks 131.107.16.0 up to 131.107.19.0. Which of the following identifies the summary route? (A) 131.107.0.0/22 (B) 131.107.16.0/24 (C) 131.107.16.0/21 (D) 131.107.16.0/22

C. The route of 13.0.0.0 remains on router R1. Because you are using static routing, there is no way for router R1 to know that the interface is down on router R2. This means that the route is still valid on router R1 as far as router R1 is concerned.

You are the network administrator for a small network that has two routers (R1 and R2, as shown in the figure below) that are connected via serial interfaces. You have used the command Ip route 13.0.0.0 255.0.0.0 12.0.0.2 on R1 to finalize configuration. What happens if the serial interface on R2 shuts down? (A) A triggered update is sent from R2 to R1. (B) A triggered update is sent from R1 to R2. (C) The route of 13.0.0.0 remains on router R1. (D) A poison reverse packet is sent from R2 to R1.

D. Through 12.0.0.2, and through 14.0.0.2 When looking at the routing table, you can see that the route to the 15.0.0.0 network has two pathways - one going through 12.0.0.2 and the other pathway going through 14.0.0.2. In this case, you will notice that the administrative distance (90) and the cost (2681856) are the same. When the cost is the same, the router will load balance between the routes.

You are troubleshooting communication on router R1. You use the show ip route command to display the routing table. Using the output of the figure below, how will information be sent from R1 to a system with the IP address of 15.0.0.25? (A) Directly through FastEthernet 0/0 (B) Always through 13.0.0.2 (C) Always through 12.0.0.2 (D) Through 12.0.0.2, and through 14.0.0.2 (E) Always through 14.0.0.2

C. Configure router on a stick You can configure the router as a router-on-a-stick, which allows the router to route between the VLANs. In order to do this, you must configure the interface on the router that is connected to the switch with sub-interfaces. You must also configure the connected port on the switch for trunking and an encapsulation protocol.

You have a router connected to a switch that has three VLANs. You would like to configure the router so that it can be used to route traffic between the three VLANs. What do you need to do? (A) Add two more routers to the network — one for each VLAN (B) Enable RIP (C) Configure router on a stick (D) Configure OSPF

B. There is no route for the 13.0.0.0 network on router R1. Routers know about networks they are connected to by default. In order to ping hosts on the 13.0.0.0 network, router R1 would need to have a route added to its routing table. You could do this by adding a static route or by loading a dynamic routing protocol.

You have configured a network as shown in the figure below. From router R1, you can ping the S0/0 interface on router R2, but you cannot ping the F0/0 interface on router R2. What is the cause of the problem? (A) The default gateway of router R2 is incorrect. (B) There is no route for the 13.0.0.0 network on router R1. (C) You need to load RIP on router R2. (D) The default gateway on router R1 is incorrect.

D. ipv6 unicast-routing You can enable IPv6 routing on the router by using the ipv6 unicast-routing command.

You would like to enable IPv6 routing on your Cisco router. What command would you use? (A) ip route ipv6 (B) ip route local ipv6 (C) ipv6 forwarding (D) ipv6 unicast-routing

C. Administrative distance In order to make the static route a backup route to the one learned by a dynamic routing protocol, you would need to alter the administrative distance of the static route to a number higher than the administrative distance of the dynamic routing protocol.

You would like to ensure that a static route is used as a backup over a route using the same pathway discovered by a dynamic routing protocol. What parameter would you change? (A) Cost (B) Bandwidth (C) Administrative distance (D) Clock rate

A. Nothing Because you are assuming that all configuration is correct, it looks like the subinterfaces have been created and the trunk port has been set.

Sue has been assigned the task of creating a router-on-a-stick network. She has configured what is shown in the figure below. Assuming all interfaces have been properly configured, what else needs to be done? (A) Nothing (B) Perform the following commands on the router: Router rip Network 192.168.1.0 Network 192.168.2.0 Network 192.168.3.0 (C) Change the trunk port to an access port (D) Perform the following commands on the router: router eigrp 1 Network 192.168.1.0 Network 192.168.2.0 Network 192.168.3.0

C. Hop count Distance vector routing protocols use hop counts as their metric. These protocols are only aware of how far something is away and not aware of bandwidth and availability of the link.

Distance vector routing protocols use which of the following as their metric? (A) Bandwidth (B) Link speed (C) Hop count (D) Available bandwidth

B. On R1 perform the following commands: R1(config)#interface f0/0 R1(config-if)#no shutdown R1(config)#interface f0/0.10 R1(config-subif)#encapsulation dot1q 10 R1(config-subif)#ip address 192.168.10.1 255.255.255.0 R1(config)#interface f0/0.20 R1(config-subif)#encapsulation dot1q 20 R1(config-subif)#ip address 192.168.20.1 255.255.255.0 D. On SW1 perform the following commands: SW1(config)#interface f0/1 SW1(config-if)#switchport mode trunk In order to configure the router on a stick, you need to configure a sub-interface on the router for each VLAN and then enable the encapsulation protocol for that VLAN. You then configure the port on the switch that is connected to the router as a trunk port.

Looking at the figure below, how would you configure the router and switch to route between the VLANs? (Select two.) (A) On R1 perform the following commands: R1(config)#interface f0/0 R1(config-if)#no shutdown R1(config)#interface f0/0.10 R1(config-subif)#encapsulation trunk 10 R1(config-subif)#ip address 192.168.10.1 255.255.255.0 R1(config)#interface f0/0.20 R1(config-subif)#encapsulation trunk 20 R1(config-subif)#ip address 192.168.20.1 255.255.255.0 (B) On R1 perform the following commands: R1(config)#interface f0/0 R1(config-if)#no shutdown R1(config)#interface f0/0.10 R1(config-subif)#encapsulation dot1q 10 R1(config-subif)#ip address 192.168.10.1 255.255.255.0 R1(config)#interface f0/0.20 R1(config-subif)#encapsulation dot1q 20 R1(config-subif)#ip address 192.168.20.1 255.255.255.0 (C) On SW1 perform the following commands: SW1(config)#interface f0/1 SW1(config-if)#switchport mode access (D) On SW1 perform the following commands: SW1(config)#interface f0/1 SW1(config-if)#switchport mode trunk

C. Through R2. R1 will send the data through R2 to get to R4 because it will use the route with the lowest administrative distance.

Looking at the figure below, when router R1 sends data to router R4, what pathway will be used? (A) R1 cannot reach R4. (B) Through R3. (C) Through R2. (D) R1 will drop all packets for R4.

A. Configure the interface that is connected to the switch as a trunk port using the same encapsulation protocol. D. Configure the interface that is connected to the switch with three sub-interfaces. In order to create a router-on-a-stick scenario to route between VLANs, you will need to configure three sub-interfaces and ensure that the interfaces are using the same encapsulation protocol as the trunk port on the switch.

Router R1 is connected to a switch that has three VLANs. You are configuring the router to route traffic between the three VLANs. What do you need to do? (Select two.) (A) Configure the interface that is connected to the switch as a trunk port using the same encapsulation protocol. (B) Enable RIP on the router. (C) Configure the interface that is connected to the switch as an access port. (D) Configure the interface that is connected to the switch with three sub-interfaces. (E) Use different encapsulation protocols on the switch and router.