Computer Science · May / June 2021 · Paper 11 · Question 7

0478

As printed in the paper

The question as text

A music company has a website that allows users to stream music. The music is stored in sound files.

Read automatically from the paper; the printed page above is exact.

Show the answer and mark scheme

7(a)(i)[4]
Four from:
(Compression) algorithm is used
No data will be removed // original file can be restored
Example of type of algorithm that would be used e.g. RLE
Repeated patterns in the music are identified
… and indexed
NOTE: If another lossless method is described, marks can be awarded.
7(a)(ii)[1]
Any one from:
To provide the highest quality of music file (that compression will allow)
The user is able to listen to the original sound file
No loss of quality for the sound file provided
7(a)(iii)[1]
Any one from:
Allow for quicker streaming speed
Would not require as much bandwidth (to stream)
Does not need as much RAM
Smoother listening experience // less lag
Will not use as much of data allowance
7(a)(iv)[2]
Two from:
Streaming speed may be slower
… and may affect listening experience // buffering may occur
User may need more bandwidth to stream
… that could be more expensive
It would be a larger file size
… so may take longer to upload
… so will take up more storage space …
… on webserver
7(b)[4]
Any four from:
Browser sends URL to DNS
… using HTTP/HTTPS
IP address is found on DNS
DNS returns IP address to the browser
Browser sends request to web server/IP address
Web server sends web pages back to browser
Browser interprets/renders the HTML (to display web pages)
Security certificates exchanged
7(c)[2]
Two from:
Web server has been flooded with traffic // web server has been sent many requests at once
… so, server is brought to a halt / crashes

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