300-820 Implementing Cisco Collaboration Hybrid and Cloud Technologies (CLHCT) Practice Questions
Prepare for 300-820 with more than an answer.
- Exam fee
- $300 USD
- Level
- Specialist
- Valid for
- 3 years
Domains covered on the exam 4
- Key Concepts25%
- Initial Expressway Configurations25%
- Mobile and Remote Access25%
- Cisco Webex Technologies25%
- 1
An organization wants to optimize media traffic for its Webex meetings. They have a large office with hundreds of users who frequently join the same Webex meetings. To reduce WAN bandwidth consumption, they deploy a Webex Video Mesh Node on-premises. How does the Video Mesh Node achieve this optimization?
(Webex Cloud) ^ | (WAN Link) | v (Corporate LAN) [Video Mesh Node] [Endpoints]Show answer details
Correct answer: B
The Webex Video Mesh Node acts as a local media cascade or bridge. When multiple on-premises endpoints join the same Webex meeting, their media streams terminate on the local Video Mesh Node. The node then establishes a single, optimized media connection to the Webex Cloud. This prevents each individual endpoint from sending its own media stream over the WAN link, significantly reducing outbound bandwidth consumption.
- 2
A university is setting up Webex and needs to automatically provision accounts for all its students and faculty from its on-premises Active Directory. They also want to enable Single Sign-On (SSO) so users can log in with their university credentials. Which two components are required to achieve both directory synchronization and SSO? (Select TWO)
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Correct answer: A, C
The Cisco Directory Connector is the software installed on-premises that synchronizes users and groups from Active Directory to the Webex Control Hub.
SSO for Webex is achieved by establishing a trust relationship between the Webex Control Hub (the Service Provider) and a SAML 2.0 compliant Identity Provider (IdP). The IdP is responsible for authenticating the users.
- 3
An administrator needs to create a dial plan element on an Expressway that prepends the string
+1to any 10-digit number that is dialed. Which Expressway component is designed for this type of number manipulation?Show answer details
Correct answer: C
Transforms are specifically designed for manipulating call aliases (dialed numbers or URIs). They use regular expressions to match a pattern and then replace it with a different string. In this case, a transform would match a 10-digit number pattern and replace it with
+1followed by the original 10 digits. Search rules use patterns to make routing decisions, but they do not modify the alias itself. - 4
What is the function of Session Traversal Utilities for NAT (STUN) in a collaboration environment?
Show answer details
Correct answer: B
STUN's primary role is discovery. An endpoint behind a NAT sends a request to a STUN server on the public internet. The STUN server examines the source IP address and port of the incoming packet and sends this information back to the endpoint. This allows the endpoint to learn its public-facing (NATed) IP address and port, which it can then advertise in its signaling (e.g., SIP/SDP) to establish a direct media path.
- 5
True or False: In a Cisco Expressway MRA deployment, the Expressway-C must have a publicly resolvable DNS A record and a public-facing IP address.
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Correct answer: B
This statement is false. The Expressway-C is the internal-facing component and should reside on the internal, trusted network. It uses a private IP address and should only have an internal DNS record. The Expressway-E is the external-facing component that has a publicly resolvable DNS record and is accessible from the internet (typically via NAT).
- 6
A hospital is deploying a Cisco MRA solution to allow doctors to use Jabber from their mobile devices. Due to strict patient data regulations, all communication must be secure. When configuring the SIP trunk security profile on CUCM for the connection to the Expressway-C, which 'Device Security Mode' is required?
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Correct answer: C
For a secure MRA deployment, the SIP signaling between the Expressway-C and CUCM must be encrypted using TLS. To enforce this, the 'Device Security Mode' on the SIP Trunk Security Profile applied to the trunk must be set to 'Encrypted'. This ensures that both signaling (via TLS) and media (via SRTP) are secure, which is a mandatory requirement for MRA to function correctly.
- 7
A user on an MRA-connected Jabber client places a call to a B2B contact at another company. The media for this call is hairpinned at the Expressway-E. Which diagram correctly illustrates the media flow?
sequenceDiagram participant JC as Jabber Client participant ExpE as Company A Exp-E participant B2B as B2B Contact JC->>ExpE: Media (RTP) ExpE->>B2B: Media (RTP) B2B->>ExpE: Media (RTP) ExpE->>JC: Media (RTP)Show answer details
Correct answer: B
Hairpinning occurs when both endpoints are external from the perspective of the internal network. The MRA client is external, and the B2B contact is also external. The media from the Jabber client goes to its home Expressway-E, which then routes the media directly to the B2B contact's public-facing system (likely their own Expressway-E). The media never needs to be 'backhauled' into the internal network via the Expressway-C, saving internal resources and bandwidth. The diagram correctly shows media flowing into and out of Company A's Expressway-E without involving any other internal components.
- 8
A collaboration engineer is designing a secure B2B video communication solution using a Cisco Expressway-C/E pair. The security policy mandates that all media streams between the organization and its partners must be encrypted. However, one key partner uses a legacy H.323 system that does not support SRTP. Which SIP media encryption mode on the traversal zone connecting to the Expressway-E would best balance the security policy with the need for interoperability with this specific partner?
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Correct answer: C
The 'Best effort' mode is the optimal choice in this scenario. It attempts to establish an encrypted SRTP call first, satisfying the security policy for all capable partners. If the remote party (the legacy H.323 system) does not support SRTP, Expressway will allow the call to proceed with unencrypted RTP. 'Force encrypted' would block the call to the legacy partner. 'Force unencrypted' would violate the security policy for all other partners. 'Auto' is a valid option but 'Best effort' is more explicit about preferring encryption while allowing fallback.
- 9
A network administrator is troubleshooting a new Mobile and Remote Access (MRA) deployment. Jabber clients outside the network can successfully register with CUCM and see presence status, but they experience no audio or video when placing calls. Internal Jabber clients function correctly. The following diagram shows the network topology:
Jabber Client | (Internet) | [Firewall-EXT] | (DMZ) | [Expressway-E] | [Firewall-INT] | (Internal LAN) | [Expressway-C] --- [CUCM]Given this scenario, which is the most likely cause of the one-way media issue?
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Correct answer: C
Successful registration and presence indicate that the signaling path (typically TCP) is working correctly. The absence of audio/video points to a problem with the media path (RTP/SRTP), which uses UDP. The most common cause for this specific symptom in an MRA deployment is the external firewall blocking the inbound UDP port range required for media to reach the Expressway-E from the internet. A missing SRV record or certificate issue would typically cause registration to fail entirely.
- 10
An organization is migrating its legacy H.323 video conferencing network to SIP. During the transition, they need their new Cisco Expressway to route calls between the two environments. Which two Expressway components are essential for enabling this H.323-to-SIP interworking? (Select TWO)
Show answer details
Correct answer: B, C
A neighbor zone for H.323 is required to establish a peering relationship with the H.323 Gatekeeper or endpoints.
The global 'Interworking mode' setting must be turned on (set to On) to allow the Expressway to translate calls between H.323 and SIP.
