Question 1

David wants to configure a single router to load balance traffic across 5 unequal cost paths. Which of the following routing protocols can be used?

Accepted Answer

For a router to be able to load balance traffic, one should use the IGRP protocol.
Key Takeaway: Of the protocols given here, only IGRP is capable of supporting unequal load balancing paths. Unequal load balancing is also known as variance. The variance command instructs the router to include routes with a metric less than n times the minimum metric route for that destination, where n is the number specified by the variance command. The variable n can take a value between 1 and 128, with the default being 1.

Question 2

Which feature does a RIP version 2 protocol use to prevent routing loops?

Accepted Answer

The RIP version 2 protocol prevents the router from routing loops with a feature known as "Split Horizon."
Key Takeaway: Split horizon is a method of preventing a routing loop in a network. The basic principle use in Split Horizon is that a particular packet is never sent back in the direction from which it was received. Distance Vector routing protocols employ the split horizon mechanism to reduce the possibility of routing loops.

Question 3

A networks uses only RIP v1 as the routing protocol. What is the maximum number of usable IP addresses that can be supported on each LAN if one Class C address block is used?

Accepted Answer

A maximum of 62 IP addresses can be supported on each LAN.
Key Takeaway: Since this network setup uses RIP v1, VLSM cannot be used. The setup has a total of 8 networks, with 4 LANs and 4 point-to-point WAN connections. Hence, a subnet mask of 255.255.255.224 should be used. This will account for a total of 8 networks, with each network supporting 30 IP addresses.

Question 4

Which of the following instances would be appropriate to use a static route on a router?

Accepted Answer

Static routes should be used to configure a route from an ISP router to a consumer network.
Key Takeaway: A static route is a route that is created manually by a network administrator. The advantages of a static route include easier configuration and absence of a routing protocol overhead. Static routes can precisely control the traffic going on your network. A route between an ISP router and the consumer network is a WAN link and is an example of a stub network. Since there is no need to run a routing protocol over the WAN links between an ISP Router and a consumer network, a static route can be configured.

Question 5

You are planning to replace all the hubs used on your corporate network with switches. Which of the following statements is true when this is done?

Accepted Answer

When hubs are the replaced with switches, the number of collision domains increase.
Key Takeaway: When a hub receives a packet, it transmits the packet to all the other PCs on the network. If two or more PCs on the network try to send packets at the same time, a collision is said to occur. A hub connected to multiple hosts is a part of a single collision domain. However, in a switch, each port creates its own collision domain.

Question 6

Refer to the WAN network shown in the figure. The Paris router needs to be implemented with an access list with some attributes. The first one is to allow HTTP traffic to access the Marketing Web server. The second one is to block any other traffic from the Internet to everything else. Which of the following access list statements should be used to accomplish these goals?

Accepted Answer

To setup these attributes on the Paris router, you need to use the statement access-list 101 permit tcp any 172.17.18.252 0.0.0.0 eq 80.
Key Takeaway: The command has an implicit deny at the end of the access list. The general syntax for a standard access list is access-list {list number} permit | deny | [source address} [source mask]. Since HTTP uses port 80, the access list statement should include this port number to permit HTTP traffic.

Question 7

David is working as a network engineer at an organization. One of his clients is planning to implement WAN technology to interconnect their regional offices to the corporate headquarters. Each of these regional offices should be connected to the corporate headquarters in a hub and spoke arrangement using packet-switched technology. Which of the following WAN technologies should David suggest?

Accepted Answer

To implement WAN technology to interconnect their regional offices to the corporate headquarters, David should suggest Frame Relay.
Key Takeaway: Frame relay puts data in a variable-size unit called a frame and leaves any necessary error correction up to the end-point, speeding up the overall data transmission. It is based on the older X.25 packet-switching technology that was designed for transmitting analog data such as voice conversations. It is often used to connect local area networks with major backbones, as well as on public-wide area networks and also in private network environments with leased lines over T-1 lines.

Question 8

You are working as a network administrator for an organization. You are to set up a fully-meshed Frame Relay network to connect four remote branch sites. How many PVCs are required in this network?

Accepted Answer

The number of PVCs required to connect four remote branch sites is 6.
Key Takeaway: The formula for calculating the number of links to achieve a full mesh is N (N−1)/2, where N is the number of locations. In this case there are 4 locations, so we will need 4(3)/2 = 6 links for the full mesh.

Question 9

You want to configure IGRP on the router. Which of the following parameters needs to be configured first as part of the IGRP routing process?

Accepted Answer

The first parameter to be configured as a part of the IGRP routing process is the Autonomous System number.
Key Takeaway: Unlike RIP, IGRP has an additional parameter with the IGRP command, the autonomous system (AS) number. In general, the AS number refers to a number assigned to a single company or organization when it registers its connection to the Internet. IGRP does not need a registered AS number. For IGRP to work, all the routers should use the same AS number.

Question 10

In an OSPF protocol, what is the maximum number of hops allowed before it deems a network unreachable?

Accepted Answer

OSPF does not have an upper limit for the number of hops.
Key Takeaway: OSPF is a link state protocol. Link state protocols do not use hops to mark networks as unreachable. They implement a steady state operation to their adjacent neighbors by periodically sending and receiving small Hello packets. If an OSPF router does not receive a Hello packet for a specified time period, it assumes that the neighbor is down. The router then runs the SPF algorithm to calculate new routes. At any cost, hop counts are not used.

Question 11

A routing table contains static, RIP, and IGRP routes destined to the same network, with each route set to its default administrative distance. Which of these routes will be the chosen as the preferred route?

Accepted Answer

The preferred route will be the static route.
Key Takeaway: IOS uses a concept called Administrative Distance to decide the route to be used. Administrative Distance is a number that denotes how believable an entire routing protocol is on a single router. The lower the number, the better, or more dependable, the routing protocol.

Question 12

David has configured the bandwidth of an OSPF interface with the "bandwidth 64" command. What is the calculated cost of the link?

Accepted Answer

The calculated cost of the link is 1562.
Key Takeaway: Cisco IOS interprets the values for the bandwidth command in kbps, so the bandwidth is configured as 64 kbps. The metric for an OSPF defaults to 100,000,000/bandwidth. So 100,000,000 / 64000 = 1562.5.

Question 13

You are a network administrator at an organization. One of the routers on your network learns two routes to a remote network, one route via OSPF and another via RIP v2. You want the router to add the route learned via RIP v2 into its routing table. What should you do to ensure that the router will use the route learned via RIP v2?

Accepted Answer

If you want the router to add the route using RIP v2 to its routing table, you must lower the value of administrative distance of RIP v2 to be lower than that of OSPF.
Key Takeaway: By default, when multiple routing protocols are configured for the same networks, the router will use the path with the lowest Administrative Distance. By default, OSPF has an AD of 110 and RIP has an AD of 120. In order to ensure that the router prefers the route learned via RIP over OSPF, the AD of the RIP route must be reduced to a value less than 120.

Question 14

You wish to limit telnet access into your Cisco router to only a single host. In order to accomplish this, access list 1 has been written to allow host 172.16.1.224 access to the router vty lines. What command would assign this access list to the Virtual Terminal Lines?

Accepted Answer

To assign the access list to the Virtual Terminal Lines, you must use the router (config-line) # access-class 1 in.
Key Takeaway: To restrict incoming and outgoing connections between a particular vty and the addresses in an access list, use the access-class command in line configuration mode.

Question 15

You have been assigned the task of connecting a new switch to an existing switch. You want to set up the VLAN Trunking Protocol to enable VLAN information passing between the switches. Which of the following should you do to accomplish this?

Accepted Answer

To be able to connect two switches and setup VTP, you must configure one of the switches as a VTP server.
Key Takeaway: VLAN Trunking Protocol is a Cisco proprietary Layer-2 messaging protocol that manages the addition, deletion, and renaming of Virtual Local Area Networks, or VLAN. To make a switch part of a VTP management domain, each switch must be configured in one of three possible VTP modes. The VTP mode assigned to a switch will determine how the switch interacts with other VTP switches in the management domain. The three VTP modes that can be assigned to a Cisco switch include server mode, client mode, and transparent mode.

Question 16

An organization has an Engineering department with 25 employees. Currently all employees in the organization are on the same network. The Engineering team is concerned about other employees being able to capture packets going across the network and obtain sensitive material. What could a network administrator do to protect Engineering network traffic from being accessed by other employees?

Accepted Answer

To separate the Engineering team's traffic from other employees, configure the Engineering team on a separate VLAN.
Key Takeaway: Virtual LANs, or VLANs, can be viewed as a group of devices on different physical LAN segments which can communicate with each other as if they are all on the same physical LAN segment. From a security standpoint, VLAN can be used to place a group of users who need high security into a VLAN so that no users outside can access traffic on the VLAN.

Question 17

Which of these WAN encapsulation types can be configured on an asynchronous serial connection?

Accepted Answer

ATM is the WAN encapsulation type that can be configured on an asynchronous serial connection.
Key Takeaway: ATM, or asynchronous transfer mode, is a dedicated-connection switching technology that organizes digital data into 53-byte cell units and transmits them over a physical medium using digital signal technology. ATM is designed to be easily implemented by hardware; hence, faster processing and switch speeds are possible. Speeds on ATM networks can reach 10 Gbps.

Question 18

David wants to set up Frame Relay for point-to-point sub-interfaces. Which of the following should he not do during this configuration?

Accepted Answer

While configuring Frame Relay for point-to-point sub-interfaces, David should not assign an IP address on the physical interface.
Key Takeaway: A point-to-point frame relay network sub-interface can have only one DLCI associated with it and it does not use frame relay map statements. If multiple point-to-point frame relay network sub-interfaces are configured for a single router and each frame relay network sub-interface has an IP address assigned to it, each IP address must be assigned from a different network or sub-network address space.

Question 19

One of your customers has an office set up with a central headquarters and four branch offices. The customer is planning to add five more branch offices in the next two years. He wants you to implement a WAN technology that is economical and facilitate the addition of these branch offices to the HQ. None of the ports on the HQ router should be left free. Which of the following should be used?

Accepted Answer

Frame Relay should be used to provide multiple connections to one router.
Key Takeaway: Frame relay network sub-interfaces divide a single frame relay interface into multiple logical interfaces. A frame relay network sub-interfaces addresses on point-to-point and multiple points. Hence, Frame Relay is economical to use.

Question 20

Which of these commands will display the CHAP authentication process that occurs between two routers on the network?

Accepted Answer

The command debug ppp authentication shows the authentication process that PPP uses between point-to-point connections.
Key Takeaway: CHAP is defined as a one-way authentication method. By default, the party that is called must authenticate the calling party. In this case, the calling party also opts to verify the identity of the called party, resulting in a two-way authentication.

Quiz 3: Networking