Section4 – Prepare infrastructure to support advanced services
QUESTION NO: 46
VOIP is being implemented in the Pass4sure network and you need to assess the need for QoS. Which of the following network problems would indicate a need to implement QoS features? (Select three)
A. Mis-routed packets
B. Excess jitter
C. Delay of critical traffic
D. Packet loss due to congestion
E. Data link layer broadcast storms
F. FTP connections unsuccessful
Answer: BCD
Explanation:
Loss, jitter, and delay are the three reasons for implementing QoS features on modern networks.
Loss is when a packet disappears on a network. Jitter is a timing mismatch between two way traffic, and delay is when a packet takes too long to get somewhere.
Incorrect Answers:
A: This would indicate a routing problem, or packets being “black-holed.” QoS would not help in this situation.
E: Broadcast storms indicate a problem on a LAN segment, such as a babbling host, too many hosts, a segment that is too large, a bad application, etc. QoS would not help in this situation.
F: If only FTP sessions were having issues, then the FTP application or FTP server should be corrected. Normally, FTP sessions are not delay sensitive due to the re-transmission nature of TCP and do not require QoS.
QUESTION NO: 47
Which statement is true about the data traffic between the access point and controller?
A.The data traffic is switched at the access point before being sent to the WLAN controller where VLAN tagging and QoS are applied.
B.The data traffic is encrypted with AES.
C.The data traffic between the access point and controller is not encrypted.
D.The data traffic is encapsulated with LWAPP.
Answer: D
Explanation:
The LAP and WLC pair use the lightweight access point protocol (LWAPP) as the tunneling mechanism.
LWAPP control messages-Exchanges that are used to configure the LAP and manage its operation. The control messages are authenticated and encrypted so that the LAP is securely controlled by only the WLC.
LWAPP data-Packets to and from wireless clients associated with the LAP. The data is encapsulated within LWAPP, but is not encrypted or otherwise secured between the LAP and WLC.
Data traffic between Access Point( AP) and Controller is encapsulated with LWAPP.
QUESTION NO: 48
Refer to the exhibit. A workstation PC is connected to the Cisco IP phone access port. Based on the configuration in the exhibit, how will the traffic be managed?
A.The IP phone access port will override the priority of the frames received from the PC.
B.The IP phone access port will trust the priority of the frames received from the PC.
C.The switch port Fa0/4 will override the priority of the frames received from the PC.
D.The switch port Fa0/4 will trust the priority for the frames received from the PC.
Answer: A
Explanation:
The PC connected to the phone, however, should normally be untrusted and have all inbound CoS values set to 0. This is mentioned here to show how trust boundaries also exist at any connected IP Phones.
Example:
interface fastethernet 0/1
switchport voice vlan 200
switchport priority extend cos 0
A switch instructs an attached IP Phone through CDP messages as to how it should extend QoS trust to its own user data switch port. To configure the trust extension, use the following interface configuration command:
Switch( config-if)# switchport priority extend {cos value | trust}
Normally, the QoS information from a PC connected to an IP Phone should not be trusted. This is because the PC’s applications might try to spoof CoS or Differentiated Services Code Point (DSCP) settings to gain premium network service. In this case, use the cos keyword so that the CoS bits are overwritten to value by the IP Phone as packets are forwarded to the switch. If CoS values from the PC cannot be trusted, they should be overwritten to a value of 0.
QUESTION NO: 49
The Company is rolling out Cisco’s Architecture for Voice, Video and Integrated Data (AVVID). Which of the following choices represent the fundamental intelligent network services in Cisco’s AVVID? (Select all that apply.)
A. Quality of Service (QoS)
B. Intelligent platforms
C. Mobility and scalability
D. Security
E. High availability
Answer: ACDE
Explanation:
By creating a robust foundation of basic connectivity and protocol implementation, Cisco AVVID Network Infrastructure addresses five primary concerns of network deployment: High availability Quality of service (QoS) Security Mobility and Scalability.
QUESTION NO: 50
Refer to the exhibit. A trunk link is connected between switch A_SW and switch D_SW. Based on the configuration shown in the exhibit, how would the traffic coming from the switch A_SW be managed?
A. The trunk port Fa0/1 on switch A_SW will trust allCoS values on the frames coming from the IP phone.
B. The trunk port Fa0/1 on switch A_SW will trust allCoS values on the frames received on the IP phone.
C. The trunk port Fa0/1 on switch D_SW will trust allCoS values on the frames coming from port Fa0/1 on A_SW.
D. The trunk port Fa0/1 on switch D_SW will trust allCoS values on the frames received on the A_SW switch port Fa0/4.
E. The trunk port Fa0/1 on switch D_SW will trust allCoS values on the frames received on the IP phone port.
Answer: C
