Stratergies to prepare for the exam?

[MJRomeo81]

Two things in relation to OSI model. Know the physical layer well (the study design certainly emphasizes this). Also understand how the OSI model relates to the TCP/IP model.

VCAA do not require you to have extensive knowledge of all layers. As long as you understand the basic ideas behind each layer, you should be fine in regards to the OSI model.

[Yendall]

Two things in relation to OSI model. Know the physical layer well (the study design certainly emphasizes this). Also understand how the OSI model relates to the TCP/IP model.

VCAA do not require you to have extensive knowledge of all layers. As long as you understand the basic ideas behind each layer, you should be fine in regards to the OSI model.

If terms of protocols, will SSL, HTTPS, FTP, POP3, IMAP, TCP, IP, SMTP suffice? Or is there others we need to know?

[MJRomeo81]

Two things in relation to OSI model. Know the physical layer well (the study design certainly emphasizes this). Also understand how the OSI model relates to the TCP/IP model.

VCAA do not require you to have extensive knowledge of all layers. As long as you understand the basic ideas behind each layer, you should be fine in regards to the OSI model.

If terms of protocols, will SSL, HTTPS, FTP, POP3, IMAP, TCP, IP, SMTP suffice? Or is there others we need to know?

That sounds like enough to me. My advice would be to prepare "written" responses for the physical layer/TCP-IP and to understand everything else in terms of a MC question. It's not likely that VCAA will ask in short answer to describe the protocols that operate on the application layer. This type of question is more suited for MC.

[billyjackson768]

Hmm... Yeah, I guess C might actually be ok when you think about it. But I still prefer to to test a value other than and end value so if there is anything wrong with your ends you should have a lot clearer picture of what's going wrong. 1200 still doesn't make sense with the rest of the logic they use. I will defiantly take a second look at these in future though, just to be sure. But VCAA is hopefully nicer than this.

A little off-topic:
Are we required to have an extensive knowledge of all layers of the OSI Model? Also do we need to memorise the protocol stack in regards to TCP/IP and know the functions of each layer?

I don't think we actually need to know much more about TCP/IP than what it is and what it does. As for the OSI model I think we just need to have a basic idea of what happens on each of the layers and an extensive knowledge on layer 1. Knowing a little more and at what layers TCP and IP operate doesn't hurt I suppose. But it's not going to be my biggest focus.

[ldee]

I'm not really confident in my knowledge for layer 1, I'll go into detail when I get home, but for now what would you guys classify as "extensive knowledge"?

[Yendall]

I'm not really confident in my knowledge for layer 1, I'll go into detail when I get home, but for now what would you guys classify as "extensive knowledge"?

I'd say:

The Physical Layer (1) of the OSI model is responsible for media, signal and binary transmission in a network. It defines how network devices work physically, which include cabling and voltage output and input. It transfers bits through the network on an electrical level. Some devices included on the Physical layer include network adapters and hubs.
Then you'd need to know the relationship with the physical level and the TCP/IP protocols:
The Physical Layer (1) is responsible to route data between devices on the same network or between the network and other devices. Without the Physical later, a network interface wouldn't be possible thus preventing the TCP/IP protocols from operating
If those are wrong, please correct me!

[paulsterio]

OSI is most likely tested in multiple choice - which means you'll need breadth of knowledge as opposed to depth of knowledge, so know as many facts as you can, but not worth going too deep into it, much better spending your time going over your case study related skills.

[Yendall]

Just a little bit of a confusing algorithm question:

Code: [Select]

PROCEDURE Calc_Qty(Product_Recipes)
BEGIN
        Open File
        Ingredient_ID <-- 1
        READ Num_Ingredients
        REPEAT
                Qty(Ingredient_ID) <-- 0
                Ingredient_ID <-- Ingredient_ID + 1
        UNTIL Ingredient_ID > Num_Ingredients
        REPEAT
                READ Product_ID, Num_Ord
                Ingredient_ID <-- 1
                REPEAT
                        Ingredient_ID <-- Ingredient_ID + 1
                        Amount_Req <-- Num_Ord * Product_Recipes(Product_ID,Ingredient_ID)
                        Qty(Ingredient_ID) <-- Qty(Ingredient_ID) + Amount_Req
                UNTIL Ingredient_ID = Num_Ingredients
        UNTIL End of File
        Close Files
ENDWe are given this test data:

VARIABLE
Num_Ingredients	3
Product ID	1
Num Ordered	10
Product_Recipes(1,1)	0.15
Product_Recipes(2,1)	0
Product_Recipes(3,1)	0.20

Upon deskchecking, I end up at the third repeat and run into an issue with array structures.

at this point in the check, these are what the variables currently equal:

Ingredient_ID = 2
Product_ID = 1
Num_Ord = 10
The line: Amount_Req <-- Num_Ord * Product_Recipes(Product_ID, Ingredient_ID) is what is confusing me.

In theory the array structure is (1,2) for Product_Receipes. However in the test data we aren't given (1,2) as  variable, instead we are given (2,1). Is this an error in the code or am i deskchecking this incorrectly. If i were to use the test data (2,1) i'd return this answer:
Amount_Req <-- Num_Ord * Product_Recipes(Product_ID,Ingredient_ID)
Amount_Req = 10 * 0 = 0
Qty(Ingredient_ID) <-- Qty(Ingredient_ID) + Amount_Req
Qty(2) <-- Qty(2) + 0
= 2
Is this correct? i feel as though it doesn't make much sense.

[Lasercookie]

The line: Amount_Req <-- Num_Ord * Product_Recipes(Product_ID, Ingredient_ID) is what is confusing me.

In theory the array structure is (1,2) for Product_Receipes. However in the test data we aren't given (1,2) as  variable, instead we are given (2,1). Is this an error in the code or am i deskchecking this incorrectly. If i were to use the test data (2,1) i'd return this answer:

Yeah I got to the stage with Product_Recipies(1,2).

I think there's a mistake with the test data given, given that they're all in the form (n,1), I'm assuming that 1 is the product ID. Given the code Product_Recipes(Product_ID, Ingredient_ID) and the fact that it'd make more sense to have Product_ID first (given a product, retrieve the ingredients).

Or the mistake could be with the line Product_Recipes(Product_ID,Ingredient_ID), where it should have been Product_Recipes(Ingredient_ID,Product_ID).

Whether we switch the bit in the code around, or the test data around, it doesn't matter. I'm going to switch the test data around to be in the form (1,n) and leave the code as given.

Product_Recipes(1,1)   0.15
Product_Recipes(1,2)   0
Product_Recipes(1,3)   0.20

What does the code do then?

In the first loop we set Qty(1), Qty(2), Qty(3) all to zero. (Qty would be an array)
What does this mean? Maybe it means that we don't have any of the ingredients at the start, or maybe it's just initialising the array (or both).

Then we get to the next loop, and Ingredient_ID is set to 1. Then we enter a while loop. Ingredient_ID is incremented. This is probably another bug in the code, we skip over Ingredient 1. I'm assuming these kind of errors are there on purpose and that we're supposed to pick them out.

Amount_Req <-- Num_Ord * Product_Recipes(1,2)
Amount_Req <-- 10 * 0 = 0

Since Product_Recipes(1,2) is zero, which implies that Ingredient 2 is not required. I think that reasoning makes sense.

Qty(Ingredient_ID) <-- Qty(Ingredient_ID) + Amount_Req
Qty(2)  <-- 0 + 0
Qty(2)  <-- 0

If the ingredient was required, we would add the values of the amount that we already have and the amount that we need. This is assuming that the first loop wasn't simply just initialising the array, but actually setting values for how much of each ingredient we had (and that happened to be 0).

I'm not too sure what this final Qty(Ingredient_ID) value actually represents (is it simply the amount we require? Surely it's not that because we could just use Amount_Req or just not bother to add Qty(Ingredient_ID) + Amount_Req together. I actually think it would make more sense to check if Qty(Ingredient_ID) >= Amount_Req to figure out we have enough of that particular ingredient on us or not, and then output information about how much more of a particular ingredient we need to get.

Then we hit, UNTIL Ingredient_ID = Num_Ingredients, this evaluates false so we repeat.

Ingredient_ID is incremented,
Amount_Req <-- Num_Ord * Product_Recipes(1,3)
Amount_Req <-- 10 * 0.20
Amount_Req <-- 2

Qty(Ingredient_ID) <-- Qty(Ingredient_ID) + Amount_Req
Qty(3)  <-- 0 + 2
Qty(3)  <-- 2

Here Ingredient_ID = Num_Ingredients so we exit the loop.

Then we do that again until we finish reading through the entire file?

[billyjackson768]

Ok... I've just gone over the 2011 VCAA exam again and question 9 in multiple choice still confuses me.

What exactally is an instruction. As opposed to a function or procedure. The text book seems to have 7 lines on "Instructions and Syntax" all of which seem to  have no bearing on why or how an instruction "modifies a variable's content". I'll check Mark Kelly's solutions again to see what he said, but I just hate the lack of explanation this text book contains here.

Edit: Mark only complains about VCCA at first publishing my answer A as correct when it is not. He gives no reason why though..

[Yendall]

Ok... I've just gone over the 2011 VCAA exam again and question 9 in multiple choice still confuses me.

What exactally is an instruction. As opposed to a function or procedure. The text book seems to have 7 lines on "Instructions and Syntax" all of which seem to  have no bearing on why or how an instruction "modifies a variable's content". I'll check Mark Kelly's solutions again to see what he said, but I just hate the lack of explanation this text book contains here.

Edit: Mark only complains about VCCA at first publishing my answer A as correct when it is not. He gives no reason why though..

Function:
Functions accept a parameter and pass data back via the name of the function. It is also seen as a block of code, rather than a single line. So like the textbook says, SIN(x) will return a value that is native to SIN. If that makes sense? Like SIN will be coded a certain way to produce an exact answer.

Procedure:
Subroutines are basically chunks of code that identify actions (that's in my words, might not make sense). But I see procedures like "Save Procedure" which can be called from within the program multiple times without having to rewrite the code.
Control Structure:
Sequence, Iteration and Selection. I see these as like REPEAT, IF THEN, ELSEIF etc.
Instruction:
Any line of code that the computer can interpret and do (laseredd has put this nicely)
How I see it is that every line of code is a form of instruction. If you're comparing it to the other definitions, an instruction can be seen as something that uses code to produce 'something'. Maybe. It's loosely defined. But in the context of this question, it's the only one that fits the description.

[billyjackson768]

Thank You! 

It actually makes sense now. I just hate answers that don't answer a question. With so many getting it wrong you'd think they'd bother to include comments with the answers as methods and further maths usually do. I think this actually reflects poorly on the approach us IT people have. You'd think we were slack or something. *alt-tabs game away*

[Yendall]

That's okay! That question annoyed the shit out of me haha

I think functions may include stuff like: Print(), Calculate(), Display() etc.
Where an instruction would be:
A = 5
B = 6
A + B = 11
I see instructions in the form of arithmetic, where you actually have to tell the variables what to do.

[MJRomeo81]

In a program, a line of code that modifies a variable's content is best described as a

A.      function.
B.      procedure.
C.      instruction.
D.      control structure.

There is a key distinction to be made.  Instructions are contained inside procedures, functions, control structures. You might have a control structure that keeps calling the same procedure/function over and over to find the maximum number in an array (with an integer variable containing the temporary max number), but it's the actual line of code (instruction) inside the method that modifies the variable's content.

[Yendall]

Because I don't have the solutions to this, I was just wondering whether i'm desk-checking appropriately:

So desk-checking the first algorithm:

CountVal = 3
A(0) = BOB
A(1) = JANE
A(2) = TMART
b.display = "bob"
temp = 0
   For i = 0 to 2
     If b.display = A(0) = "bob" then
         Temp = 1
     End if
   End For
Temp = 1
If temp = 0 then (skip this)
Elseif temp = 1 Then

    CountVal = 2

    While countval < 4 = 2
       Countval = Countval + 1 = 3
    EndWhile
End if
End
So we are left with:
Countval = 3
Temp = 1
b.Display = "bob"

For this algorithm we are asked to show what Object.Writeline will produce if Countval = 2
Begin {Action B}

For i = (2 - 2) to (2-1)
For i = 0 to 1
Object.Writeline(A(0))
End For

CountVal = CountVal + 1
Now because i doesn't increment, will the end result be: Object.Writeline("Bob") ?
Next we are asked what CountVal will equal.
Because 'i' doesn't increment (and it should), the For is terminated:
2 = 2 + 1 = 3
Countval = 3
How I would've written this algorithm is:

Begin {Action B}

    For i = (countVal - 2_ to (countVal - 1)
    Object.Writeline(A(i))
    i = i + 1
    End For
   
    countVal = countVal + 1
End
So it would produce A(1) = Jane
Is this all correct? Thanks!