多选题What are three factors used to determine the amount of bandwidth that is required for a single VoIP call？（）AcodecBlink speedCLayer 2 encapsulationDpacket overhead （IP/UDP/RTP）Elink delayFtotal number of simultaneous calls that are allowed

第1题：

The Acme company has determined that during its busiest hours， the average number of internal VoIP calls across the WAN link is four （4）. Since this is an average， the WAN link has been sized for six （6） calls with no call admission control. What will happen when a seventh call is attempted across the WAN link？ （）

• A、the seventh call is routed via the PSTN
• B、the call is denied and the original six （6） calls remain
• C、the call is completed and the first call is dropped
• D、the call is completed， but all calls have quality issues
• E、the call is completed but the seventh call has quality issues

第2题：

What are two reasons to implement H·323 gatekeepers？（）

• A、 to eliminate the need for VoIP gateways
• B、 to scale a VoIP installation with multiple gateways
• C、 to provide call admission control and limit the number of simultaneous calls on the network 
• D、 to meet the requirement to control H·323 gateways on a LAN
• E、 to accept call requests and reduce the load on the gateway

第3题：

What does Grade of Service (GoS) mean? （）

• A、Number of available subscriber services
• B、Number of unsuccessful call set-ups due to congestion
• C、Channel utilization
• D、Number of successful call set-ups
• E、Number of dropped calls

第4题：

Which statement is true about IP telephony calls？（）

• A、 A Voice over IP （VoIP） packet consists of the voice payload， IP header， TCP header， RTP header， and  Layer 2 link header.
• B、 The voice carrier stream uses H323 to set up， maintain， and tear down call endpoints.
• C、 Call control signaling uses Real-Time Transport Protocol （RTP） packets that contain actual voice  samples.
• D、 The sum of bandwidth necessary for each major application， including voice， video， and data， should not exceed 75 percent of the total available bandwidth for each link.

第5题：

In a Teleworker deployment with a single IP phone connected to a Cisco 831 router, select the true statement regarding Call Admission Control.（）

• A、RSVP is a required configuration to support conference calls without voice packet loss. 
• B、The QoS configuration on the 831 router must always provision sufficient bandwidth for two RTP streams. 
• C、Call admission control is an issue only when using hardware DSP resources. 
• D、When using the conference call features on a 7960 IP phone, only one RTP stream is present regardless of how many extensions are on the conference.

第6题：

A branch router is configured with an egress QoS policy that was designed for a total number of 10 concurrent VOIP Calls. Due to Expansion， 15 VOIP Calls are now running over the link， but after the 14th call was established， all calls were affected and the voice quality was dramatically degraded. Assuming that there is enough bandwidth on the link for all of this traffic， which part of the QOS configuration should be updated due to the new traffic profile？（）

• A、Increase the shaping rate for the priority queue.
• B、Remove the policer applied on the priority queue.
• C、Remove the shaper applied on the preiority queue.
• D、Increase the policing rate for the priority queue.

第7题：

Which two statements are true about the function of CAC？（）

• A、CAC provides guaranteed voice quality on a link.
• B、CAC artificially limits the number of concurrent voice calls.
• C、CAC is used to control the amount of bandwidth that is taken by a call on a link.
• D、CAC prevents oversubscription of WAN resources that is caused by too much voice traffic.
• E、CAC allows an unlimited number of voice calls while severely restricting，if necessary，other forms of traffic.
• F、CAC solves voice congestion problems by using QoS to give priority to UDP traffic.

第8题：

第9题：

第10题：

第11题：

第12题：

第13题：

Which statement is true about the Call Admission Control （CAC） feature in VoIP networks？（）

• A、 CAC is used to allocate enough bandwidth for the number of calls that are allowed on the VoIP network.
• B、 CAC is used to protect the quality of the voice calls by preventing call establishment if enough resources are not available on the network.
• C、 CAC provides queuing mechanisms for voice calls if the packets exceed the configured or budgeted rate.
• D、 In a VoIP network the CAC can be replaced with the LLQ QoS mechanism if it has been properly implemented.

第14题：

VoIP网络数据中传输的语音数据的封装格式为（）。

• A、IP∣UDP∣RTP∣语音数据
• B、IP∣TCP∣RTP∣语音数据
• C、IP∣语音数据
• D、IP∣UDP∣RTCP∣RTP∣语音数据

第15题：

What are three factors used to determine the amount of bandwidth that is required for a single VoIP call？（）

• A、codec
• B、link speed
• C、Layer 2 encapsulation
• D、packet overhead （IP/UDP/RTP）
• E、link delay
• F、total number of simultaneous calls that are allowed

第16题：

What three pieces of information can be used in an extended access list to filter traffic (Choose three.)（）。

• A、protocol
• B、VLAN number
• C、TCP or UDP port numbers
• D、source switch port number
• E、source IP address and destination IP address
• F、source MAC address and destination MAC address

第17题：

What is the primary benefit of Single Number Reach？（）

• A、 Employees can receive calls at their desk and cell phone simultaneously.
• B、 Customers can call one number to reach all employees.
• C、 Employees can have their calls forwarded to the receptionist.
• D、 Customers can call any office number and the receptionist receives the call.

第18题：

Which three pieces of information are used to calculate the total bandwidth of a VoIP call？（）

• A、the packetization size
• B、the serialization of the interface
• C、the quantization
• D、the packet rate
• E、the UDP overhead
• F、the TCP overhead

第19题：

第20题：

第21题：

第22题：

第23题：

第24题：