CCNA 3 v6.0 (Scaling Networks v6) Chapter 5: Dynamic Routing: Check Your Understanding Questions Answers
1. Which dynamic routing protocol was developed to interconnect different Internet service providers?
- BGP
- EIGRP
- OSPF
- RIP
Explanation: BGP is a protocol developed to interconnect different levels of ISPs as well as ISPs and some of their larger private clients.
2. Which routing protocol is limited to smaller network implementations because it does not accommodate growth for larger networks?
- EIGRP
- IS-IS
- RIP
- OSPF
Explanation: RIP was created with a metric that does not support larger networks. Other routing protocols, including OSPF, EIGRP, and IS-IS, scale well and accommodate growth and larger networks.
3. What two tasks do dynamic routing protocols perform? (Choose two.)
- Assigning IP addressing
- Discovering hosts
- Doing network discovery
- Propagating host default gateways
- Updating and maintaining routing tables
Explanation: Routing protocols dynamically discover neighbors to exchange and update routing information.
4. Which two statements are true regarding classless routing protocols? (Choose two.)
- Classless routing protocols reduce the amount of address space available in an organization.
- Classless routing protocols send complete routing table updates to all neighbors.
- Classless routing protocols support VLSM and CIDR.
- Classless routing protocols send subnet mask information in routing updates.
- RIPv1 is a classless routing protocols.
Explanation: Classless routing protocols include subnet mask information in their routing updates and therefore support VLSM and CIDR.
5. In the context of routing protocols, what is convergence time?
- A measure of protocol configuration complexity
- The amount of time a network administrator needs to configure a routing protocol in a small to medium-sized network
- The amount of time for the routing tables to achieve a consistent state after a topology change
- The capability to transport data, video, and voice over the same media
Explanation: Time to convergence defines how quickly the routers in the network topology share routing information and reach a state of consistent knowledge.
6. Which two events will trigger the sending of a link-state packet by a link-state routing protocol? (Choose two.)
- A change in the topology
- A link to a neighbor router becoming congested
- The initial startup of the routing protocol process
- The requirement to periodically flood link-state packets to all neighbors
- The router update timer expiring
Explanation: A link-state packet (LSP) is sent only during initial startup of the routing protocol process on a router and whenever there is a change in the topology, including a link going down or coming up or a neighbor adjacency being established or broken. Data traffic congestion does not directly influence routing protocol behavior. LSPs are not flooded periodically, and update timers are not relevant to LSPs.
7. Which two requirements are necessary before a router configured with a linkstate routing protocol can build and send its link-state packets? (Choose two.)
- The router has built its link-state database.
- The router has constructed an SPF tree.
- The router has determined the costs associated with its active links.
- The router has established its adjacencies.
- The routing table has been refreshed.
Explanation: A link-state enabled router must determine the cost of its active links and establish adjacencies before it can send an LSP. Once LSPs are received, the router can construct its SPF tree and build its LSDB.
8. Which two statements describe the OSPF routing protocol? (Choose two.)
- It automatically summarizes networks at the classful boundaries.
- It calculates its metric by using bandwidth.
- It has an administrative distance of 120.
- It uses Dijkstra’s algorithm to build the SPF tree.
- It is used primarily as an EGP.
Explanation: The metric of OSPF is cost, which is based on the cumulative bandwidth of the links to the destination network.
9. How do EIGRP routers establish and maintain neighbor relationships?
- They compare known routes to information received in updates.
- They dynamically learn new routes from neighbors.
- They exchange hello packets with neighboring routers.
- They exchange neighbor tables with directly attached routers.
- They exchange routing tables with directly attached routers.
Explanation: Like OSPF, EIGRP uses hello packets to establish and maintain neighbor adjacencies.
10. Which OSPF component is identical in all routers in an OSPF area after convergence?
- Adjacency database
- Link-state database
- Routing table
- SPF tree
Explanation: Each OSPF router views the network differently, as the root of a unique SPF tree. Each router builds adjacencies based on its own position in the topology. Each routing table in the area is developed individually through the application of the SPF algorithm. The link-state database for an area, however, must reflect the same information for all routers.
11. Which of the following is a function of OSPF hello packets?
- To discover neighbors and build adjacencies between them
- To ensure database synchronization between routers
- To request specific link-state records from neighbor routers
- To send specifically requested link-state records
Explanation: The OSPF hello packet serves three primary functions: discover OSPF neighbors and establish adjacencies, advertise parameters that OSPF neighbors must agree on, and elect the DR and BDR.
12. Which two parameters does EIGRP use as metrics to select the best path to reach a network? (Choose two.)
- Bandwidth
- Confidentiality
- Delay
- Hop count
- Jitter
- Resiliency
Explanation: EIGRP uses bandwidth and delay by default, and it can also be configured to use load and reliability as metrics for selecting the best path to reach a network.
13. Which statement describes a route that has been learned dynamically?
- It has an administrative distance of 1.
- It is automatically updated and maintained by routing protocols.
- It is identified by the prefix C in the routing table.
- It is unaffected by changes in the topology of the network.
Explanation: Dynamically learned routes are constantly updated and maintained by routing protocols.
14. Which two factors are important when deciding which interior gateway routing protocol to use? (Choose two.)
- Campus backbone architecture
- ISP selection
- Scalability
- Speed of convergence
- The autonomous system that is used
Explanation: There are several factors to consider when selecting a routing protocol to implement. Two of them are scalability and speed of convergence. The other options listed here are irrelevant.