2013 Latest Cisco DESGN (640-864)Exam 170-180

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QUESTION 176
Area Border Router (ABR) is defined by which protocol?
A. Enhanced Interior Gateway Routing Protocol (EIGRP)
B. OSPF
C. On-Demand Routing (ODR)
D. IS-IS
Correct Answer: B
Section: Routing Explanation

ABR (Area Border Router) – Routers that connect to more than one OSPF area

Cisco Press CCDA 640-864 Official Certification Guide Fourth Edition

QUESTION 177
Which queuing mechanism establishes four interface output queues that will be used for traffic scheduling?
A. Priority queuing (PQ)
B. First-in, first-out (FIFO)
C. Weighted fair queuing (WFQ)
D. Custom queuing (CQ)
Correct Answer: A
Section: QoS Explanation
Congestion Management
Two types of output queues are available on routers: the hardware queue and the software queue. The hardware queue uses the strategy of first in, first out (FIFO). The software queue schedules packets first and then places them in the hardware queue. Keep in mind that the software queue is used only during periods of congestion. The software queue uses QoS techniques such as priority queuing, custom queuing, weighted fair queuing, class-based weighted fair queuing, low-latency queuing, and traffic shaping and policing.
Priority Queuing
Priority queuing (PQ) is a queuing method that establishes four interface output queues that serve different priority levels: high, medium, default, and low. Unfortunately, PQ can starve other queues if too much data is in one queue because higher-priority queues must be emptied before lowerpriority queues.
Custom Queuing
Custom queuing (CQ) uses up to 16 individual output queues. Byte size limits are assigned to each queue so that when the limit is reached, it proceeds to the next queue. The network operator can customize these byte size limits. CQ is fairer than PQ because it allows some level of service to all traffic. This queuing method is considering legacy due to the improvements in the queuing methods.
Weighted Fair Queuing
Weighted fair queuing (WFQ) ensures that traffic is separated into individual flows or sessions without requiring that you define ACLs. WFQ uses two categories to group sessions: high bandwidth and low bandwidth. Low-bandwidth traffic has priority over high-bandwidth traffic. High bandwidth traffic shares the service according to assigned weight values. WFQ is the default QoS mechanism on interfaces below 2.0 Mbps.
Cisco Press CCDA 640-864 Official Certification Guide Fourth Edition, Chapter 6

QUESTION 178
Which option is not valid for using the public Internet as a backup WAN medium?
A. IP Security (IPSec) tunnels
B. Shared PVC
C. IP routing without constraints
D. Generic Routing Encapsulation (GRE) tunnels
Correct Answer: B
Section: WAN VPN Explanation

The Internet as a WAN Backup Technology

This section describes the Internet as an alternative option for a failed WAN connection. This type of connection is considered best-effort and does not guarantee any bandwidth. Common methods for connecting noncontiguous private networks over a public IP network include the following.
The following sections describe these methods.
Routing Without Constraints
When relying on the Internet to provide a backup for branch ofces, a company must fully cooperate with the ISP and announce its networks. The backup networkthe Internettherefore becomes aware of the companys data, because it is sent unencrypted.
Layer 3 Tunneling with GRE and IPsec
Layer 3 tunneling uses a Layer 3 protocol to transport over another Layer 3 network. Typically, Layer 3 tunneling is used either to connect two noncontiguous parts of a non-IP network over an IP network or to connect two IP networks over a backbone IP network, possibly hiding the IP addressing details of the two networks from the backbone IP network. Following are the two Layer 3 tunneling methods for connecting noncontiguous private networks over a public IP network:
GRE enables simple and exible deployment of basic IP VPNs. Deployment is easy; however, tunnel provisioning is not very scalable in a full-mesh network because every point-to-point association must be dened separately. The packet payload is not protected against sniffing and unauthorized changes (no encryption is used), and no sender authentication occurs. Using GRE tunnels as a mechanism for backup links has several drawbacks, including administrative overhead, scaling to large numbers of tunnels, and processing overhead of the GRE encapsulation.
Authorized Self-Study Guide Designing for Cisco Internetwork Solutions (DESGN), Second Edition

QUESTION 179
For the following items, which is an SP Edge module in the Enterprise Composite Network model?
A. Core layer
B. Edge distribution
C. Public Switched Telephone Network (PSTN) service
D. Server farm
Correct Answer: C
Section: Architecture Explanation

Service Provider Edge Module

The SP edge module, shown in Figure 2-12, consists of SP edge services such as the following
Figure, WAN/Internet SP Edge Module
Enterprises use SPs to acquire network services. ISPs offer enterprises access to the Internet. ISPs can route the enterprises networks to their network and to upstream and peer Internet providers. Some ISPs can provide Internet services with DSL access. Connectivity with multiple ISPs was described in the section, Internet Edge. For voice services, PSTN providers offer access to the global public voice network. For the enterprise network, the PSTN lets dialup users access the enterprise via analog or cellular wireless technologies. It is also used for WAN backup using ISDN services. WAN SPs offer MPLS, Frame Relay, ATM, and other WAN services for enterprise site-to-site connectivity with permanent connections.
Cisco Press CCDA 640-864 Official Certification Guide Fourth Edition, Chapter 2

QUESTION 180
Which method will be used to secure a network against man-in-the-middle attack?
A. Two-factor authentication
B. Management module
C. Encryption
D. Firewall
Correct Answer: C
Section: Security Explanation

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