Review Questions

1.	Which of the following are advantages of hierarchical design? (Choose all that apply.) Fault tolerance Scalability Ease of manageability Predictability All of the above
2.	Which of the following are layers in Cisco’s three-layer hierarchical design? (Choose all that apply.) Backbone Core End node Access Distribution
3.	Which of the following should be included at the core layer? (Choose all that apply.) Packet filtering Firewalls Fast throughput Fault tolerance Additional devices
4.	How many layers of hierarchy should you add below the access layer? None One Two Three Four
5.	Which of the following are permitted at the distribution layer? (Choose all that apply.) Packet filtering Access lists Queuing Redundant WAN connections Firewalls
6.	Which of the following are generally associated with the core layer of the network? (Choose all that apply.) Security High capacity Fault tolerance Packet filtering
7.	Which of the following are modules in the Enterprise Campus functional area of the Enterprise Composite Network Model? (Choose all that apply.) Enterprise Edge Server Farm Network Management All of the above
8.	Which of the following methods will allow IP workstations to dynamically locate routers? (Choose all that apply.) HSRP Workstation listening to routing protocols Router location request Proxy ARP RTMP
9.	You need to add a new site to your hierarchical network. Which of the following are possible places to connect the new site into your existing network? Access layer Distribution layer Core layer The corporate office
10.	When designing fault-tolerant network topologies, which of the following can DDR accomplish? (Choose all that apply.) Back up a primary link in case of failure. Promote a router from the access layer to the distribution layer. Populate Enhanced IGRP tables with routing information. Back up a primary link in case of heavy network load. Back up a primary link in case of routing problems.
11.	Select the topology in which it is easiest to troubleshoot connectivity issues. Bus Ring Hierarchical Mesh
12.	Which three of the following are functional areas of the Enterprise Composite Network Model? Enterprise Campus Core Distribution Enterprise Edge Service Provider Edge
13.	You have a T1 link from an access layer router to a distribution layer router and a BRI DDR connection to another distribution layer router. The DDR is configured to run in case of failure. Which of the following do you have? Proxy ARP Fault tolerance Load balancing HSRP None of the above
14.	Which of the following are advantages of Layer 3 switching over Layer 2 switching in the core of a network? (Choose all that apply.) Broadcast control Spanning tree Latency Load balancing Router peering
15.	You have two routers that will be participating in HSRP. How many IP and MAC addresses will the workstations use for their default router? None, they communicate with the phantom router. One Two Three
16.	What is the problem caused during IP load balancing by routing protocols that use hop count as a metric? Pinhole congestion Failure Convergence delay You can’t load balance IP.
17.	You have a T1 link from an access layer router to a distribution layer router and a BRI DDR connection to another access layer router. The DDR is configured to run in case of failure. Which of the following do you have? Proxy ARP Pinhole congestion Load balancing HSRP None of the above
18.	How can redundant links be added into a hierarchical design without breaking the hierarchy? Full mesh Partial mesh Creating a ring Redundant links can’t be added into a hierarchical design without breaking the hierarchy.
19.	Your customer has a hierarchical network design. Redundancy and reliability are most important at which layer? Backbone Distribution Access Core
20.	In general, at which layer of Cisco’s hierarchical model are functions such as packet filtering, route summarization, and routing protocol redistribution performed? Access Distribution Core Enterprise Campus

Answers

1.	E All of the answers are advantages of hierarchical design and provide many benefits when managing and troubleshooting networks.
2.	B, D, E Cisco’s three-layer hierarchical model is made up of the core, distribution, and access layers. These three layers are not always clearly defined within each and every network design, but they serve as a guideline.
3.	C, D The core layer is responsible for high-speed traffic flow and redundancy.
4.	A The access layer where users connect is the bottom layer and should not have any other layers below it.
5.	A, B, C, D, E All of these traffic-management technologies are usually implemented at the distribution layer, but they can extend into the access layer.
6.	B, C The core layer is concerned with capacity and fault tolerance. Packet filtering and security are generally implemented at the distribution layer.
7.	B, C The four modules of the Enterprise Campus functional area are Campus Infrastructure, Network Management, Server Farm, and Edge Distribution. Enterprise Edge is a separate functional area, not a module of the Enterprise Campus functional area.
8.	B, D Proxy ARP is used by IP workstations, while IPX and AppleTalk workstations listen for routing protocol updates, or they request them from the network.
9.	B You should avoid changing the diameter and consistency of the core layer, and the access layer is for “local site” client access.
10.	A, D, E Floating routes and OSPF demand circuits allow DDR to bring up a second link in the event of routing problems.
11.	C One of the main design purposes of hierarchical networks is troubleshooting. The other purpose is network management.
12.	A, D, E The three functional areas of the Enterprise Composite Network model are Enterprise Campus, Enterprise Edge, and Service Provider Edge.
13.	B From a single access layer router, multiple distribution layer connections provide for fault tolerance.
14.	A, D, E Layer 3 switching aids in broadcast control, load balancing, and router peering.
15.	B The advantage of HSRP is that the clients never need to change their default router configuration, even when a router failure occurs. They are always configured to use the phantom router IP and MAC addresses.
16.	A RIP and IGRP use hop count as a metric and cannot detect links of different speeds. Consequently, they can’t detect when redundant links are unequally used.
17.	E You have broken the hierarchical model by connecting two access layer routers.
18.	B A full mesh addition would break the hierarchy and create a flat network design.
19.	D The core layer affects all other layers in the hierarchical network design, so redundancy and reliability are crucial at this layer.
20.	B Packet filtering, route summarization, and redistribution are generally handled at the distribution layer.