[Year 12 IT Apps] VITTA ITA exam 2 - my ideas of errata

[Russell Edwards]

Hi Mark, I agree with most of what you have said, just a couple of  
minor points

On 15/10/2007, at 1:36 PM, Mark Kelly wrote:
> Question 1
> Which of the following enables several LANS to connect over a WAN?
> Suggested answer: D. Router.
>
> A router protects a LAN from the outside world, but its role is not  
> principally to enable communications.  I suspect the best answer  
> would be a modem.

The primary role of the router is indeed to enable communications  
between two or more networks. It may include a firewall of some sort  
(=protection from the outside world) but need not.   A modem is not  
necessary as you may have a data link that doesn't require modulation/ 
demodulation-- though you'd be hard pressed to find one that could  
offer distances that classify as "wide area"!

> Question 3
> Which type of backup uses two sets of backup media and backs up the  
> most recent changes on the second media?
> Suggested answer: B. Differential.
>
> This can’t be right.,  The question is very odd.  Two sets of  
> backup media? From http://www.backuptool.com/incremental% 
> 20backup.htm...

I suppose what they're getting at is that incremental backups might  
use more than twos set of media. But in fact, the terms are about  
_what_ you backup, _when_ -- not _where_ you put the data (i.e. media).

> A modem is, for most people today, a digital device for ADSL or  
> cable internet that has no modulation or demodulation happening!   
> The question should have referred to analogue modems if it wanted  
> this answer.

No, ADSL and cable are still analog modems. ADSL goes over copper  
line just as dialup, simply using a much higher (analog) bandwidth  
than plain dialup and avoiding the voice band. Cable modems (afaik)  
use an optic fibre data link so again this is a modem, as a carrier  
wave (in this case a light wave) is modulated to transport data.   
Even wireless, 3G or satellite internet will rely on a pair of modems  
(with an electromagnetic wave as a carrier) as part of the link, even  
though the term isn't usually used in reference to them.

cheers

Russell Edwards
Whittlesea Secondary College


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