aco quiz 3

In DASH (Dynamic, Adaptive Streaming over HTTP), a server divides a video file into chunks that ... (pick best completion from below)

... are stored, each encoded at multiple rates (video quality). The client plays the video chunk-by-chunk, with each chunk requested at encoding rate that fits the available bandwidth at the time.

Compute the Internet checksum value for these two 16-bit words: 11110101 11010011 and 10110011 01000100

01010110 11100111

Compute the Internet checksum value for these two 16-bit words: 01000001 11000100 and 00100000 00101011

10011110 00010000

What information does the type "A" resource record hold in the DNS database? Check all that apply.

A hostname and an IP address.

Check all of the services below that are provided by the UDP protocol.

A message abstraction

Why is the UDP header length field needed?

Because the payload section can be of variable length, and this lets UDP know where the segment ends

A unit of video, each of which may be encoded at multiple different rates, stored in different files.

Chunk Explanation

The transport layer sits on top of the network layer, and provides its services using the services provided to it by the network layer. Thus it's important that we know what is meant by the network layer's "best effort" delivery service. True or False: The network layer's best-effort delivery service means that IP makes its "best effort" to deliver segments between communicating hosts, but it makes no guarantees. In particular, it does not guarantee segment delivery, it does not guarantee orderly delivery of segments, and it does not guarantee the integrity of the data in the segments.

Correct! The network layer's best effort service doesn't really provide much service at all, does it?

An approach that allows a client to adapt the encoding rate of retrieved video to network congestion conditions

DASH

What is the value of caching in the local DNS name server? Check all that apply.

DNS caching results in less load elsewhere in DNS, when the reply to a query is found in the local cache. DNS caching provides for faster replies, if the reply to the query is found in the cache.

A CDN approach that stores content in access networks, close to clients.

Enter Deep

Which of the fields below are in a UDP segment header? [Hint: note the use of the word "header" in this question statement.]

Length (of UDP header plus payload Internet checksum Source port number Destination port number

A file containing the location and encoding rate of files corresponding to video segments in a video.

Manifest

What is meant by transport-layer demultiplexing?

Receiving a transport-layer segment from the network layer, extracting the payload (data) and delivering the data to the correct socket.

Check all of the services below that are provided by the TCP protocol.

Reliable data delivery.4. A congestion control service5. A byte stream abstraction6. A flow-control service7. In-order data delivery

What approach is taken by a CDN to stream content to hundreds of thousands of simultaneous users?

Store/serve multiple copies of videos at multiple geographically distributed sites.

What is meant by transport-layer multiplexing?

Taking data from one socket (one of possibly many sockets), encapsulating a data chuck with header information - thereby creating a transport layer segment - and eventually passing this segment to the network layer.

Over what set of bytes is the checksum field in the UDP header computed over?

The entire UDP segment, except the checksum field itself, and the IP sender and receive address fields

Check all of the phrases below that state a true property of a local DNS server

The local DNS server record for a remote host is sometimes different from that of the authoritative server for that host. The local DNS server can decrease the name-to-IP-address resolution time experienced by a querying local host over the case when a DNS is resolved via querying into the DNS hierarchy

Which of the following statements are true about a checksum? Hint: more than one statement is true.

The sender-computed checksum value is often included in a checksum field within a packet header. A checksum is computed at a sender by considering each byte within a packet as a number, and then adding these numbers (each number representing a bytes) together to compute a sum (which is known as a checksum). The receiver of a packet with a checksum field will add up the received bytes, just as the sender did, and compare this locally-computed checksum with the checksum value in the packet header. If these two v

Manifest file. What is the purpose of a manifest file in a streaming multimedia setting?

To let a client know where it can retrieve different video segments, encoded at different rates

Where is transport-layer functionality primarily implemented?

Transport layer functions are implemented primarily at the hosts at the "edge" of the network

True or False: When computing the Internet checksum for two numbers, a single flipped bit (i.e., in just one of the two numbers) will always result in a changed checksum.

True

True or False: When computing the Internet checksum for two numbers, a single flipped bit in each of the two numbers will always result in a changed checksum

false

True or False: When multiple TCP clients send TCP segments to the same destination port number at a receiving host, those segments (from different senders) will always be directed to the same socket at the receiving host.

false

True or False: It is possible for two TCP segments with source port 80 to be sent by the sending host to different clients.

true

True or False: It is possible for two UDP segments to be sent from the same socket with source port 5723 at a server to two different clients.

true

True or False: On the sending side, the UDP sender will take each application-layer chunk of data written into a UDP socket and send it in a distinct UDP datagram. And then on the receiving side, UDP will deliver a segment's payload into the appropriate socket, preserving the application-defined message boundary.

true

True or False: When multiple UDP clients send UDP segments to the same destination port number at a receiving host, those segments (from different senders) will always be directed to the same socket at the receiving host.

true

true or False: The transport layer provides for host-to-host delivery service

true