CLCOR Hard Questions — 25 Difficult Questions

Question 1

Which THREE items are included in a standard SIP REGISTER request?

Accepted Answer

To Header. The 'To', 'From', and 'Contact' headers are mandatory in a SIP REGISTER request.

Answer

Alert-Info

Answer

Body (SDP)

Question 2

A CUBE is configured for H.450.3 call forwarding, but it is not working. What is the most likely cause?

Accepted Answer

Incompatible signaling protocol. H.450.3 is an H.323 supplementary service, which requires specific H.323 configuration and is often incompatible with SIP-based CUBE deployments without proper interworking.

Answer

Dial-peer not defined

Answer

Codec mismatch

Answer

SIP profile missing

Question 3

A CUBE is receiving calls but rejecting them due to '488 Not Acceptable Here'. What is the most likely reason?

Accepted Answer

Codec mismatch. 488 usually indicates a mismatch in media capabilities (codecs or SDP) offered vs what is configured on the dial-peer.

Answer

Authentication failure

Answer

SIP registration expired

Answer

Dial-peer inactive

Question 4

Which THREE commands are used to configure a SIP profile in CUBE?

Accepted Answer

voice-class sip-profiles apply. SIP profiles require creating a voice class, defining the match/modify rules, and applying it to a dial-peer.

Answer

dial-peer voice

Answer

sip-ua

Question 5

Which THREE of the following are required for the successful operation of the Webex Hybrid Calendar service? (Choose three)

Accepted Answer

A valid configuration in Control Hub.. The Hybrid Calendar requires a properly configured service account, the connector host (Expressway), and an integration configuration in Control Hub.

Answer

A Cisco Unified Communications Manager cluster.

Answer

A public PSTN trunk.

Question 6

When configuring Hybrid Call Service for Cisco Unified Communications Manager, which specific requirement must be met for the Expressway-C and Expressway-E pair?

Accepted Answer

They must be configured with a Unified Communications traversal zone.. The Expressway pair must be registered with the Webex cloud to enable the connector, and specific traversal zones must be configured to pass the signaling traffic.

Answer

They must use the same certificate authority as the CUCM nodes.

Answer

They must use a public IP address on the Expressway-C.

Answer

They must be in the same subnet.

Question 7

When troubleshooting a Hybrid Service, you need to collect 'Diagnostic Logs'. Where do you download these from?

Accepted Answer

The Expressway-C Maintenance > Diagnostics page.. The Expressway provides a dedicated 'Maintenance > Diagnostics' section where you can generate and download comprehensive log bundles for support analysis.

Answer

The Webex App settings menu.

Answer

The Cisco CLI using the 'log collect' command.

Answer

Control Hub under the Troubleshooting tab.

Question 8

Which THREE of the following items are verified during the Webex Hybrid Service connector installation? (Choose three)

Accepted Answer

Active Directory service account privileges.. The installation process validates that the Expressway-C can communicate with the cloud, that the certificates are trusted, and that the service account has the necessary permissions.

Answer

The local PBX manufacturer.

Answer

User's home network speed.

Question 9

You are deploying a CUBE (Cisco Unified Border Element) for SIP trunking. Which feature allows CUBE to hide the internal network topology from the service provider?

Accepted Answer

SIP Header Normalization. SIP Header Manipulation/Normalization is used to rewrite headers and remove sensitive internal network information like private IP addresses.

Answer

Media Proxy

Answer

Call Admission Control (CAC)

Answer

Registration Proxy

Question 10

You are configuring DNS SRV records to support Jabber service discovery. Which domain format is correct for the _collab-edge._tls record?

Accepted Answer

_collab-edge._tls.example.com. The _collab-edge._tls record is used by Cisco Expressway-E for MRA discovery, and it must point to the FQDN of the Expressway-E cluster.

Answer

_tls._collab-edge.example.com

Answer

collab-edge.example.com._tls

Answer

_collab-edge._tcp.example.com

Question 11

Which THREE of the following troubleshooting steps should be performed if a Webex Hybrid connector is showing 'Down' in Control Hub? (Choose three)

Accepted Answer

Restart the Management Service on the Expressway-C.. When a connector fails, the administrator should verify network connectivity, check the service status on the Expressway, and examine the local logs for errors.

Answer

Re-provision the Active Directory domain controller.

Answer

Upgrade the CUCM cluster software.

Question 12

An administrator is troubleshooting a failed Hybrid Calendar setup. The 'Connector' shows as 'Down' in Control Hub. What is the most likely reason?

Accepted Answer

The Expressway-C host cannot reach the cloud over port 443.. If the service connector is down, it usually indicates a loss of connectivity from the Expressway-C host to the cloud, or an issue with the management service process on the appliance.

Answer

The calendar integration license is invalid.

Answer

The user's password expired.

Answer

The user is not in the correct group in Active Directory.

Question 13

You need to ensure that the Webex App can perform 'Click-to-Call' from a browser. What must be installed on the user's machine?

Accepted Answer

Webex browser extension.. The 'Webex Extension' for browsers enables the integration of click-to-call functionality from web pages directly into the Webex App.

Answer

The Hybrid Calendar connector.

Answer

A local PSTN gateway.

Answer

Cisco Jabber for Windows.

Question 14

You are designing a high availability solution for Cisco Unity Connection. Which service must be running and correctly configured on both the primary and secondary servers to facilitate automatic failover?

Accepted Answer

Connection High Availability. Cisco Unity Connection uses the Connection High Availability service to synchronize data and heartbeat between the cluster nodes.

Answer

Cisco Tomcat Service

Answer

Cisco Database Layer Monitor

Answer

Cisco Unity Connection Message Transfer Agent

Question 15

When troubleshooting Webex Calling, which THREE factors are critical for maintaining call quality over a hybrid network?

Accepted Answer

Quality of Service (QoS) tagging. QoS, bandwidth, and latency are the three pillars of maintaining high-quality voice in hybrid environments.

Answer

Local database replication speed

Answer

Hardware firewall bypass

Question 16

Which THREE of the following are recommended steps when designing a secure signaling path between CUCM and a CUBE gateway?

Accepted Answer

Install and trust CA certificates. Using SIP Trunk Security Profiles, installing the correct CA certificates, and enabling TLS are the three pillars of securing the SIP signaling path.

Answer

Disable SIP digest authentication

Answer

Enable H.323 Fast Start

Question 17

You are troubleshooting high latency for Webex media. Which tool in Control Hub provides the best visibility into the path taken by the media packets?

Accepted Answer

Calling Quality of Service (QoS) Dashboard. The 'Webex Calling Media Quality' dashboard or the 'Troubleshooting' section in Control Hub provides detailed metrics on hop-by-hop latency.

Answer

Device logs

Answer

Packet Capture (PCAP) from the cloud

Answer

Network Analysis Tool

Question 18

You are implementing Webex Calling with a Local Gateway. The requirement is to maintain internal dial plan transparency for existing extension-to-extension dialing. What must you configure?

Accepted Answer

Location-based routing and dial plan normalization. To maintain dialing transparency, the dial plan must be synchronized or normalized between the local gateway and the Webex Calling cloud dial plan.

Answer

Global Dial Plan Replication

Answer

Directory sync override

Answer

PSTN overflow routing

Question 19

Which THREE components are involved in the Webex Hybrid Media Service architecture?

Accepted Answer

Expressway-C. The architecture relies on Expressway-C, Media nodes, and the cloud-based management platform.

Answer

Cloud PSTN Gateway

Answer

CUCM Media Resource Group

Question 20

You are designing a high-availability solution for Cisco Expressway. Which element is required to load-balance traffic between multiple Expressway nodes?

Accepted Answer

External Load Balancer. An external load balancer is required to distribute incoming traffic across the cluster of Expressway-E nodes.

Answer

Cisco CUBE redundancy

Answer

Cisco UCM Group

Answer

DNS Round Robin only