Free H11-861-V4-0 sample questions

Correct answer: The VPN concentrator's access control list (ACL) is not configured to allow the full range of UDP ports used for RTP media traffic from the VPN client subnet to the MCU's IP address.

This is the most likely cause. One-way audio is a classic symptom of a firewall or NAT traversal issue where signaling gets through, but the media stream (RTP) is blocked in one direction. Since the problem is specific to VPN users and signaling is confirmed to be working, the issue points to a restrictive rule on the VPN concentrator or firewall that is not permitting the dynamic UDP ports used by RTP to pass from the remote clients to the MCU. A SIP ALG issue would likely cause call setup failures, not intermittent one-way audio. Jitter buffer issues would cause choppy audio, not a complete lack of it. Codec mismatch would typically result in no audio at all or a call failure, not an intermittent one-way problem.

Correct answers: Implement H.235 with Annex D for certificate-based authentication and media encryption.; Configure all H.323 endpoints with a primary and a secondary gatekeeper address, enabling alternate gatekeeper functionality.

To meet the encryption requirement in an H.323 environment, H.235 is the correct standard. To meet the gatekeeper failover requirement, endpoints must be configured with an alternate (secondary) gatekeeper address. The SMC cluster provides management redundancy but doesn't handle endpoint registration failover. IPsec is a network-layer solution and not the native H.323 method. Using G.711 is a codec choice and unrelated to failover or encryption.

Correct answer: Huawei Service Management Center (SMC)

The Huawei Service Management Center (SMC) is the core platform for managing the entire collaboration solution, including endpoints like the IdeaHub. It provides centralized user management, device management, and role-based access control (RBAC). Administrators can use the SMC to create different user roles (e.g., 'Faculty', 'Student') and assign specific permissions to each role, which are then enforced on the IdeaHubs. The MCU handles conference bridging, iManager is for broader network management, and CloudLink is the client/platform, but the SMC is the central point for this type of granular permission control.

Correct answer: True

This statement is true. This is the fundamental principle of SVC. Unlike traditional Advanced Video Coding (AVC) where the MCU must transcode separate streams for each endpoint's capability, SVC uses a layered encoding approach. The MCU sends one stream containing multiple layers (a base layer for low resolution, and enhancement layers for higher resolutions/framerates). Each endpoint then extracts and decodes the layers it needs, significantly reducing the processing load on the MCU and improving efficiency, especially in large conferences with diverse endpoints.

Correct answer: There is no compatible media codec or SRTP profile defined in the Session Description Protocol (SDP) offer from the CloudLink client that the third-party endpoint can support.

The SIP response code '488 Not Acceptable Here' specifically indicates a media-related incompatibility. The receiving endpoint is stating that it cannot accept the session as described in the SDP of the INVITE. This is almost always due to a lack of a common audio/video codec, an unsupported encryption profile (SRTP), or other incompatible media parameters. Incorrect credentials would result in a '401 Unauthorized' or '407 Proxy Authentication Required'. A busy endpoint would respond with '486 Busy Here'. A network routing issue would likely result in a timeout or a '404 Not Found'.

Correct answer: The cascading link has been configured with insufficient bandwidth to carry the multi-stream continuous presence video.

This is the most probable cause. When cascading MCUs, the link between them must have enough bandwidth to carry the video streams for the desired layout. If only the active speaker is being transmitted, it suggests the system has automatically fallen back to a lower-bandwidth, single-stream mode because the allocated bandwidth for the cascading link is too low to support the full continuous presence layout. Codec mismatch or incorrect IP addresses would likely cause the cascade to fail entirely, not just downgrade the video layout. Encryption settings would also typically result in a complete connection failure if mismatched.

Correct answer: Type of Service (ToS)

The Type of Service (ToS) field in the IPv4 header is an 8-bit field used for Quality of Service. The Differentiated Services (DiffServ) architecture redefines this field. The first 6 bits of the ToS field are used for the DSCP value, and the last 2 bits are used for Explicit Congestion Notification (ECN). Therefore, DSCP values are carried within the ToS field.

Correct answer: Dereverberation

While AEC is crucial for canceling echo caused by the loudspeaker's sound being picked up by the microphone, the 'hollow' sound described is a classic symptom of reverberation (sound waves reflecting off hard surfaces). The Dereverberation feature is an advanced algorithm specifically designed to identify and suppress these reflected sound waves, improving clarity. AGC normalizes volume levels, and ANS reduces steady background noise like fans, but Dereverberation directly addresses the problem of room acoustics and reflected sound.

Correct answers: Using Transport Layer Security (TLS) to encrypt the SIP signaling messages.; Using Secure Real-time Transport Protocol (SRTP) to encrypt the audio and video media streams.; Enforcing SIP Digest Authentication to verify the identity of users and endpoints.

Comprehensive SIP security involves three key areas: authenticating the user/device, encrypting the call setup (signaling), and encrypting the call content (media). SIP Digest Authentication handles authentication. TLS encrypts the signaling (call control messages like INVITE and BYE). SRTP encrypts the actual audio/video media packets. 802.1p is for QoS, not security. H.235 is the security standard for H.323, not SIP.

Correct answer: Utilize Scalable Video Coding (SVC) to allow the TE60 to send a high-quality stream and the factory endpoint to send a robust, lower-quality stream, with the MCU efficiently routing the appropriate layers to each participant.

This scenario, with highly asymmetric endpoint capabilities and network conditions, is a perfect use case for Scalable Video Coding (SVC). SVC allows each endpoint to send a stream optimized for its capabilities. The high-end TE60 can send a multi-layered HD stream, while the factory cart can send a more robust, lower-resolution base layer stream. The MCU can then forward the appropriate layers to each endpoint without needing to perform CPU-intensive transcoding for every participant. This provides the best possible quality for the design center while maintaining a stable connection for the factory floor. Forcing a low baseline (A) penalizes the high-end user. H.265 (B) helps with compression but doesn't solve the asymmetry as elegantly as SVC. H.239 (D) is for content sharing, not the main video stream.