AQA COMP3 June 2012 Exam Thread

For question two, the os will have a network software layer which will intercept commands that reference networked resources. It may also have some server os functions as it may have to deal with requests from other clients. So it will provide services and resources to the other networked clients.


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do we need to know the purpose of a device driver?

yea they are used to communicate with the OS and control the hardware (device). They are written in a low level language and are not already on the OS to reduce the size of the OS, to allow compatibility of different manufacturers and allow a range of hardware.

do we need to know what is meant by leased line networking and dial-up networking?

do we need to know what is meant by leased line networking and dial-up networking?

For anyone worrying about asynchronous transmission and digital certificates, just managed to learn both in less than 30 mins. Fairly logical after a bit of practice.

A hashes the message to produce a message digest
This is then encrypted using A's private key to produce a signature
The signature is then added to the message
The message is then encrypted using B's public key

The message is decrypted using B's private key
The signature is then decrypted using A's public key to reproduce the message digest
The message is the rehashed to produce a message digest
The two digests are then compared if they match then the message has not been tampered


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Thanks mate . That makes a lot of sense now. I hope it comes in the exam for six marks

yeah, it's not that complicated, bond has asperger's syndrome though so he can't explain things in a logical way at all

I don't understand this question.


(b) Bus local area networks such as Ethernet operate in baseband mode. Wide area networks operate in broadband mode. Give two reasons why wide area networks are operated in broadband mode. (2 marks)

Two reasons:
Wide area networks expensive to install;
Wide area networks expensive to maintain;
Wide area networks involve long distances;
Can allow multiple data stream to keep costs down;
Many channels needed to cope with high volume of traffic
Or enables more users to use network without experiencing congestion;
R Faster
R Can work over longer distances
R More than one user will want to use it simultaneously
R Cheaper, more efficient

Why would a reason to use broadband be it is expensive and why is more than one user will want to use it at the same time rejected. I thought the whole concept of braodband was you can transmit multiple data at the time because of the swith at the center re routes the data where it wants to go.

This summarises the entire computing course pretty well.

WIDE area networks are expensive to install, broadband or baseband, so broadband is used because ti doesn't make business sense to spend a lot of money and only be able to transmit a single data stream.

Is that from a past paper? Very badly worded by the sounds of it