Overlay Video Streaming and Decentralized Web

Indicate the correct answers in video streaming (2 correct answers). Playback starts only after the complete file is downloaded. Video is played while it is still being transferred. A buffer is typically used to smooth jitter and bandwidth variations. Video streaming does not require any buffering. Playback is impossible until all chunks are received.

Which strategies can be applied when the buffer runs empty? (2 correct answers). Pause playback (stalling). Increase the video bit rate. Skip frames and continue playback. Reset the network connection. Reboot the client.

Which statements are correct for live streaming? (2 correct answers). Perfect playback synchronization is always possible. Content is often generated while streamed. Playback lag is used as synchronization metric. Clients usually stall instead of skipping missing data. Preloading of the full video is common.

Which are characteristics of VoD streaming? (3 correct answers). Content is pre-generated. Playback synchronization between users is required. Users watch independently. Missing data usually leads to playback stalling. Content must be generated live.

Which methods can be used to deliver video streams? (3 correct answers). IP Unicast. IP Broadcast. IP Multicast. DNS Anycast. ARP flooding.

Which statements about IP multicast are correct? (2 correct answers). Routers replicate packets. It is widely deployed at Internet scale. It violates the stateless principle of IP routers. It is only used for file sharing. It requires no router state.

Why are overlays used for streaming? (2 correct answers). IP multicast is not scalable on the Internet. To remove the need for video compression. To offload the streaming source. To increase packet loss. To avoid buffering.

Which statements describe managed overlays? (2 correct answers). CDN nodes act as proxies. Clients participate as upload peers. Delivery is transparent to clients. No servers are used. They are fully decentralized.

Which are properties of unmanaged overlays? (2 correct answers). Clients become peers. Overlay delivery is transparent. Peers contribute upload bandwidth. They require a central router. They only use unicast.

Which statements are correct about single-tree topology? (2 correct answers). Video is pushed down the tree. Peer churn cannot disconnect subtrees. Only inner nodes contribute upload. Maintenance overhead is zero. Playback lag increases with tree height.

Which are true about multi-tree overlays? (2 correct answers). Video is split into substreams. Each peer is only in one tree. Peers can be inner nodes in at least one tree. No topology maintenance is required. It is less resilient than single-tree.

Which are correct about mesh-based streaming? (2 correct answers). Pull-based coordination. Stable data paths exist. Very robust to peer failure. No coordination overhead. Chunks are pushed by default.

Which are correct about the hybrid tree/mesh? (2 correct answers). Stable peers form a backbone. Unstable peers form a mesh. It has no overhead. It is less stable than pure mesh. It does not require peer classification.

Which statements are correct about PPLive? (3 correct answers). Uses a mesh-based pull approach. Uses a tracker for neighbor discovery. Blocks are discarded after playback. Only the source distributes all blocks. Uses tree-based push only.

Which are true about BitTorrent Live? (2 correct answers). Uses clubs to distribute substreams. Does not use trackers. Uses BitTorrent concepts. Only works for VoD. Does not use peers.

Which are correct about clubs in BitTorrent Live? (2 correct answers). Each club distributes one substream. Peers can join unlimited clubs. The source is member of all clubs. Clubs do not use flooding. Clubs do not exchange data.

Which are correct about Scalable Video Coding (SVC)? (3 correct answers). It is an extension of H.264. It supports spatial scalability. It supports temporal scalability. It removes buffering needs. It cannot adapt to bandwidth.

Which are correct in the SVC layers? (2 correct answers). Base layer is (0,0,0). Layers depend on higher layers. Layers depend on lower layers. Only one dimension is scalable. (2,2,2) is base layer.

Which statements are correct? (2 correct answers). QoS directly equals user experience. QoE reflects perceived quality. Packet loss may affect QoE differently. QoE ignores environment. QoS includes stalling perception.

Which are correct about MS? (2 correct answers). It is based on user studies. It uses a 0–1 scale. It uses a 5-point scale. It is fully objective. It ignores human perception.

Which are correct about VQM? (2 correct answers). Scores range from 0 to 1. 1 means best quality. It is standardized by ITU. It is purely subjective. It only works for H.264.

Which are correct about WebRTC? (2 correct answers). Enables real-time communication in browsers. Requires plugin installation. Supports audio, video, and data. Works only in private networks. Does not support encryption.

Which are correct about NAT? (2 correct answers). NAT hides private IP addresses. NAT simplifies peer-to-peer connectivity. NAT blocks incoming connections. NAT removes need for STUN. NAT increases transparency.

Which are correct in STUN? (2 correct answers). Discovers public IP and port. Relays all traffic. Helps NAT traversal. Encrypts video. Stores media.

Which are correct about TURN? (2 correct answers). Acts as a relay server. Used when direct connection fails. Replaces STUN completely. Works only for file sharing. Blocks media traffic.

Which are correct about IPFS? (2 correct answers). Uses content addressing. Requires central servers. Is peer-to-peer. Uses DNS exclusively. Deletes data after use.

Which are correct about the IPFS design? (2 correct answers). Data is identified by hashes. Content disappears if one peer leaves. Multiple peers can store same data. It is censorship friendly. Requires a master node.

Which are correct? (2 correct answers). Overlays replicate at application level. IP multicast replicates at router level. Both scale equally. Overlays require no coordination. IP multicast is widely used on the Internet.

Which are correct about the Playback lag? (2 correct answers). It measures synchronization quality. It is irrelevant for live streaming. It is time between chunk creation and playback. It depends only on codec. It is always zero.

Which are correct? (2 correct answers). File sharing requires full download before playback. Streaming allows watch-while-download. File sharing has strict real-time constraints. Streaming has no buffer. File sharing is synchronized.