Computer Science · May / June 2026 · Paper 12 · Question 3

0478

As printed in the paper

The question as text

A video streaming service uses hexadecimal to display error codes when problems occur with their videos.

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

Show the answer and mark scheme

3(a)[1]
D
3(b)[2]
0001 0101 0010
0011 0000 1111
3(c)[2]
475
AE8
3(d)[2]
162
260
3(e)(i)[2]
Header
Trailer
3(e)(ii)[3]
Three from:
It examines/analyses/searches packet to find the destination IP address // It reads the destination IP address for a packet
It sends/transmits/forwards packet towards/to its destination
It determines/assigns/controls/selects the route/path each packet takes
… which is the fastest/most efficient/shortest route/path // which is the route with the least traffic
Uses/updates a routing table
… to keep track of the most efficient routes/paths
Checks/updates the packets hop count/time to live/TTL
… and disregards packets when they have reached their hop count
3(f)(i)[2]
Two from:
It uses electromagnets
It has platters (to store data)
(Platters are) divided into tracks and sectors
It has a read/write head/arm
3(f)(ii)[1]
Solid-state // solid-state drive // SSD
3(g)(i)[2]
Two from:
They want to retain the original version (of the video) // Original version (of the video) can be recovered
(The videos) will be the highest/high quality // The quality will not be reduced/will be retained // Artifacting will be less likely
Storage space is not a concern // File sizes are small enough (with lossless)
3(g)(ii)[1]
One from:
Smaller file size
The videos would use less storage/memory space
The time taken to transmit the videos would be shorter // Faster transmission/upload/download
Less bandwidth would be used to transmit the videos
Video would be less likely to buffer when streaming
3(g)(iii)[4]
Four from:
A compression algorithm is used
… such as RLE
Repeating frames/pixels are identified …
Repeating samples are identified (for sound) …
… and indexed // by example
Eliminating redundancy // Uses temporal redundancy
… by recording the differences between each frame/amplitude (for sound)

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