CLCOR Practice Test 4 — 10 Questions

Question 1

Which THREE network conditions contribute to poor VoIP call quality in an RTP stream?

Accepted Answer

Latency. Latency (A) is correct because one-way delay above roughly 150 ms degrades RTP voice interactivity, causing talk-over and echo that the jitter buffer cannot fix. Jitter (C) is correct because variable inter-packet arrival times force the jitter buffer to either underrun (clipping) or grow (added delay), directly harming voice quality. Packet Loss (D) is correct because dropped RTP packets cannot be retransmitted in real time, so codecs conceal the gaps, producing robotic or choppy audio. High MTU (B) is not inherently harmful—fragmentation is the real risk—and Fast switching (E) is a LAN forwarding behavior, not a WAN impairment affecting RTP quality.

Answer

High MTU

Answer

Fast switching

Question 2

You are designing Quality of Service (QoS) for a Cisco Collaboration deployment. The customer wants to ensure that voice traffic is prioritized over data traffic. Which marking should be applied to voice bearer traffic on Cisco IP Phones and switches?

Accepted Answer

IP DSCP EF (46) and CoS 5.. Voice bearer traffic must be marked with DSCP EF (46) and CoS 5 to ensure it receives priority treatment across the network. This is the Cisco best practice for QoS. The other markings are used for different traffic types, such as video or signaling, and would not provide the required priority for voice.

Answer

IP DSCP AF31 (26) and CoS 3.

Answer

IP DSCP CS3 (24) and CoS 3.

Answer

IP DSCP AF41 (34) and CoS 4.

Question 3

You are deploying a Webex Room device in a hybrid environment. What is the benefit of registering it to Webex instead of on-premises CUCM?

Accepted Answer

It enables full access to Webex cloud features like whiteboarding and AI-driven metrics.. Registering a Webex Room device to Webex (cloud) rather than on-premises CUCM unlocks the full Webex cloud feature set, including Webex Assistant, whiteboarding, AI-driven meeting metrics, and cloud-based management through Control Hub. Cloud registration also simplifies updates and provides native Webex Meetings join experience. On-premises CUCM registration limits the device to CUCM call control features and requires expressway/Collaboration Edge for cloud service access.

Answer

It allows the device to function without an internet connection.

Answer

It reduces the bandwidth required for video calls.

Answer

It forces the device to use on-premises media routing.

Question 4

You are observing that video traffic is marked as DSCP 0. How can you fix this at the network level without changing the endpoint configuration?

Accepted Answer

Use an ACL to match the traffic and a policy-map to re-mark it. When video endpoints send DSCP 0 (best-effort), the marking must be corrected in the network path. A class-map matches the traffic (e.g., by ACL identifying RTP/Video over the correct port range), and a policy-map with a set dscp command re-marks it to the desired value such as AF41 for interactive video. Applying this via MQC (Modular QoS CLI) on the ingress interface fixes the marking without touching the endpoint configuration.

Answer

Disable traffic shaping

Answer

Change the interface speed

Answer

Enable auto-qos on the interface

Question 5

Which deployment model should be chosen for Cloud Connected PSTN (CCP) if the organization wants to leverage their existing carrier contracts?

Accepted Answer

Cloud Connected PSTN (CCP). Cloud Connected PSTN (CCP) lets an organization bring its own PSTN carrier into Webex Calling by peering the carrier's network with the Webex Calling cloud, so existing carrier contracts, rates, and DIDs are preserved. This is the deployment model explicitly designed for 'use my existing carrier' scenarios, as opposed to Cisco-provided PSTN or on-premises gateways. The carrier must be a Webex Calling CCP partner.

Answer

Local Gateway PSTN

Answer

Webex Calling PSTN via Cisco

Answer

Webex Calling Dedicated Instance

Question 6

An engineer needs to verify the current active calls on a Cisco IOS XE voice gateway and see details such as call legs, codecs, and durations. Which command should be used?

Accepted Answer

show call active voice brief. The 'show call active voice brief' command is the correct tool to verify active calls on a Cisco IOS XE voice gateway. It lists each call leg with critical details such as calling/called numbers, codec, and duration, allowing an engineer to quickly assess current call activity. Other commands either focus on configuration or are protocol-specific.

Answer

show sip-ua calls

Answer

show voice call status

Answer

show dial-peer voice summary

Question 7

A collaboration engineer is deploying a new Cisco Webex Room Kit in a conference room. The endpoint will send 1080p video at 3 Mbps. The network administrator needs to ensure that the video traffic is marked with the appropriate DSCP value and receives proper treatment in the QoS policy. Which DSCP value should be used for this interactive video traffic?

Accepted Answer

AF41 (34). The correct DSCP for interactive video is AF41 (34). This marking ensures that video traffic is treated with assured forwarding and low drop precedence, providing a balance between priority and bandwidth guarantees. Voice uses EF, signaling uses CS3, and interactive video uses AF41. This hierarchy ensures that voice gets the highest priority, followed by video, then signaling, then data. Marking video as AF41 allows network devices to apply appropriate queuing and congestion management.

Answer

CS4 (32)

Answer

AF31 (26)

Answer

EF (46)

Question 8

A network designer is implementing QoS for a Cisco Collaboration deployment. Which two statements about the trust boundary in a Cisco QoS design are true? (Choose two.)

Accepted Answer

Cisco IP Phones are typically trusted to mark voice traffic correctly, so the switch port should trust DSCP.. The trust boundary should be as close to the source as possible, and Cisco IP Phones can be trusted to mark voice and signaling traffic correctly. This ensures that QoS markings are preserved end-to-end and that other devices trust them. Placing the boundary at the core or trusting all PC traffic is not recommended.

Answer

All traffic from a PC connected to an IP Phone should be trusted by default.

Answer

The trust boundary should be placed at the core layer to centralize QoS marking.

Answer

The trust boundary is only necessary for voice media, not for call signaling.

Question 9

A network administrator is troubleshooting one-way audio issues between a Cisco IP Phone and a Cisco TelePresence endpoint. The path traverses a router with a configured class-map. Which command would you use to verify the packet markings on the ingress interface?

Accepted Answer

show policy-map interface. The command `show policy-map interface` displays the actual packet markings and QoS statistics applied to an interface by a policy-map. Since the class-map is referenced within a policy-map, this command shows the number of packets matching each class and the marking actions (e.g., DSCP, CoS) that were applied. This is the only option that directly verifies the markings on the ingress interface.

Answer

show class-map configuration

Answer

show ip rtp statistics

Answer

show qos interface

Question 10

A company is implementing Webex Edge Connect. They require a dedicated circuit. Who must they coordinate with to set up the physical connection?

Accepted Answer

A certified Cisco Webex Edge Connect partner.. Webex Edge Connect is a dedicated, private connectivity option between a customer's network and the Webex cloud, delivered via a Cisco-certified partner that has direct peering into Cisco's Edge Connect locations. The physical cross-connect, BGP peering, and circuit turn-up must be coordinated with that certified partner because they own the interconnection into Cisco's data centers. Cisco does not sell the circuit directly, and the customer's local ISP alone cannot provision the private handoff into Webex.

Answer

The local Internet Service Provider only.

Answer

The Webex Control Hub automated provisioning tool.

Answer

Cisco Technical Support