A Letter to the department

Hi all

I have sent a letter to the department regarding the marks I received for assignments 4 and 5 and I thought that I should post what I sent them in case there are any more out there that might have similar worries.

I have subsequently submitted a request on myUNISA to deregister from the module so I will not be writing the exam in any case but I sent the e-mail on principle.

<<FYI: I got 22 credits for ass1, I stupidly didn't do ass2 or 3 since was going through a very busy patch and I thought I could make up the credits with the written assignments. I got 50% (20 credits) for ass4 and 25% (10 credits) for ass5.>>

Good luck in the exams to those who qualify
____________________________________________________________________
Attached are the scanned pages of the assignments 4 and 5 as returned by your department. I have just downloaded the solutions for these assignments from the Osprey server and compared my answers to your solutions. I do not see how you can justify awarding me such low marks since in my opinion, my answers resemble yours not literally, but semantically.

In addition to this, please could you check your solution answers for Ass4 Question 2 - they contradict what is printed in the textbook - and Ass5 Question Question 4 - ironically your solution is incomplete (your table does not have a row for transmission methods).

As a suggestion for future years, please would you include a mark allocation along with the questions so that students can, at least, know how many points to mention. As it stands, I have no idea how marks were awarded.

This request must in no way be interpreted as a request for exemption to write the exam. Based on the accumulated credits I achieved, I deemed it futile to complete and hand in the last assignment so there is absolutely no way that I will have enough credits to qualify for exam admission. I will be placing a request to deregister from this module in any case on the chance that I might recouperate some of the fees.

This request is merely for the sake of principle. I have absolutely no idea how your marker, A Laubscher, can justify awarding me such low marks. I have never been more shocked or bewildered.

Thank you in advance and I look forward to the revised marks.

R. Escott

I also received 20 credits for assignment 5 with a lot of "incomplete" remarks. I expected to receive at least 80% - 90% for the assignment.

I have also received 20 credits only for assignment 5 yet I was expecting 30 to 37. I have not yet got the marked sheets so there is no way I can know how marks were awarded. Any how I suspect in accurate marking am yet to cross check.

Well I received a copy of an e-mail from one of the staff to another saying that my assignment 4 was going to be checked and that the request to the other person was to check my assignment 5.

On my assignments that I got back, there were only ticks and "incompletes". There were no actual marks written anywhere so I couldn't even check to see if there was an adding error.

In any case, I've already submitted my request for cancellation via myUNISA and I'm just waiting for it to be processed.

You guys are lucky in having got something back!

I have not recieved marks for Ass 5 or 6 yet and also 20 for Ass 4 but have not had it returned as yet. I find it extremely improbable that I could have only half correct.

I have an long ago masters degree in electronic engineering and know a lot about these stuff - I do the course as an update and to obtain recent credits to allow future postgrad studies. I can not check what or how they marked since the marked ass has not been returned.

Dear Students

The assignments were credited on the following basis [Please refer tutorial letter 203 Page 2]:


Commendable / complete effort : 40 credits
Satisfactory Effort : 20 credits
Poor effort : 10 credits

Hope this answers your query about credit allocation for assignments. Due to the back log that happened in the assignment department we received your assignments very late and had to process it very fast which resulted in less comments than usual.

About your second point, please point out which solution you found contradicting to the text book. [Question 2 of Assignment 04 had subdivisions.

Now, there was an errata in Tutorial letter 203.Pleaser refer to that for an answer to your question regarding Assignment 05.

Please be reminded to refer your tutorial letters before contacting lecturers

Kind Regards
Lecturers

This should have been better communicated to students long before the due date of assignemt 5. I only needed a few credits to get exam admission and completed the assignment only to the degree I thought was enough for admission. To my shock I got the marks on Aug 2'nd and realized I still needed 2 credits for admission. I then scrambled to do ass 6, which will hopefully be marked. I shudder to think what whould have happened if I only received the marks a week or 2 later.

> About your second point, please point out which
> solution you found contradicting to the text book.
> [Question 2 of Assignment 04 had subdivisions.

Well, virtually the whole of Ass4Q2 is wrong. Here's the question:

2.1 Physical Layer
2.2 Application Layer
2.3 Administrative layer
2.4 Transport Layer
2.5 Session Layer
2.6 MAC sublayer
2.7 Network layer
2.8 Data Link layer
2.9 Presentation layer
2.10 Logical Link Control sublayer

a. Manages signalling to and from physical network connections.
b. Packages data in frames appropriate to network transmission method
c Provides an interface to the network layer protocols.
d. Manages access to the physical medium
e. Ensures accurate delivery of data
f. Allow hosts and applications to use a common language.
e. Ensures accurate delivery of data
g. Establishes, maintains and terminates user connections.
h. Provides the interface between applications and network for interpreting program requests and requirements.
i. Translates network addresses into their physical counterparts.

Your Solution:

2.1  Physical layer..................d
2.2  Application layer...............a
2.4  Transport layer.................g
2.5  Session layer...................i
2.6  MAC sublayer....................h
2.7  Network layer...................e
2.8  Data Link layer.................b
2.9  Presentation layer..............f
2.10 Logical Link Control sublayer...c

These are the answers I gave and their mark:

2.1 a  x
2.2 h  x
2.3 no such layer
2.4 e  x
2.5 g  x
2.6 d  x
2.7 i  x
2.8 b  _/
2.9 f  _/
2.10 c _/

You mention in the solution that the following textbook references:

2.1 - 2.5 (Ref p56)
2.6       (Ref p53)
2.7-2.9   (Ref p56)
2.10      (Ref p53)

This is what the textbook ACTUALLY says:
p53:
The upper sublayer of the Data Link layer, called the LLC (Logical Link Control) sublayer, provides an interface to the Network layer protocols, manages flow control, and issues requests for transmission for data that has suffered errors. This agrees with the solution for 2.10 The MAC (Media Access Control) sublayer, the lower sublayer of the Data Link layer, manages access to the physical medium. This contradicts the solution to 2.6

The rest of your solutions refer to p56. I assume this is table 2-1. The table is as follows:

Application (Layer 7) : Provides interface between software applications and network for interpreting applications' requests and requirements Contradicts solution for 2.2

Presentation (Layer 6) : Allows hosts and applications to use a common language; performs data formatting, encryption, and compression. Agrees with solution to 2.9

Session (Layer 5) : Establishes, maintains, and terminates user connections. Contradicts solution to 2.5

Transport (Layer 4) : Ensures accurate delivery of data through flow control, segmentation and reassembly, error correction, and acknowledgment Contradicts solution to 2.4

Network (Layer 3) : Establishes network connections; translates network addresses into their physical counterparts and determines routing. Contradicts solution to 2.7

Data Link (Layer 2) : Packages data in frames appropriate to network transmission method Agrees with the solution to 2.8

Physical (Layer 1) : Manages signaling to and from physical network connections Contradicts solution to 2.1

> Now, there was an errata in Tutorial letter
> 203.Pleaser refer to that for an answer to your
> question regarding Assignment 05.
> 
> Please be reminded to refer your tutorial letters
> before contacting lecturers
>

That is good advice and I normally DO read the tut letters. Unfortunately, I have not received ANY of the 200-series of tut letters from your department. The only reason I know about these errors is because I downloaded the solutions to ass 4 and 5 from osprey.

Here's your solution

When one clicks a button to retrieve an e-mail message from the server, the Application layer services on ones computer accept data from the mail application and formulate a request meant for the mail server software. The services add an application header to the data that the program wants to send. The header contains information about the e-mail applications requirements and transfers the request to the Presentation layer in the form of a protocol data unit (PDU).

The Presentation layer first determines whether and how it should format or encrypt the data request if the mail client requires encryption, contains graphics or formatted text, it will add that information to the PDU in a presentation header. Then, the Presentation layer sends its request to the Session layer.

The Session layer adds a session header that contains information about how the modem communicates with the network and passes the PDU to the Transport layer.

At the Transport layer, the PDU, the clients request for mail as well as the headers added by previous layers are broken down into segments whose maximum size is dictated by the type of network transmission method in use. Segments are assigned sequence identifiers and this information becomes part of the transport header. Protocols also add checksum, flow control, and acknowledgement data to the transport header. These segments are passed, one at a time, to the Network layer.

Network layer protocols add logical addressing information to the segments so that the clients request will be properly routed to the mail server and the mail server will respond to the clients computer. The information is contained in the network header. With the addition of network address information, the pieces of data are called packets, which are passed on to the Data Link layer.

At the Data Link layer, protocols add a header to the front of each packet and a trailer to the end of each packet to make frames – that is, the Data Link layers protocols encapsulate the Network layer packets. Built into each frame are error checking means. After verifying that the data has not been damaged, the frames are passed to the Physical layer.

At the Physical layer, the clients request for mail, in the form of many frames, hits the NIC. The Physical layer does not interpret the frames or add information to the frames; it simply transmits them over the phone line connected to the client modem, across the office network and to the mail server after the binary digits (bits), or ones and zeroes, have been converted to electrical pulses.

As the frames arrive at the server, the servers Physical layer accepts the frames and transfers them to the Data Link layer. The mail server begins to unravel the clients request, reversing the process described above, until it responds to one's request with its own transmission, beginning from its Application layer.

Here's my Answer

When a client needs to interact with a server across a network connection, it communicates with the application layer. The application layer adds a header portion to the clients data in accordance with the specific protocol the client requested. The application layer then passes this data to the presentation layer, which translates it into a commonly understood format and could even compress or encrypt the data. The presentation layer appends a header portion to the front of the data explaining what has been done to the it after receiving it from the application level and then forwards this on to the session layer.

The session layer creates, maintains and terminates connections between nodes of the network. While the session is active, it passes data from the presentation layer on to the transport layer. The transport layer splits the data from the session layer into segments that are efficiently sized to maximise data transmission. This layer is responsible for making sure that each segment is received by the other side and joined together again. A header containing the segmentation order and verification data precedes each segment. The checksum in the header makes sure that it is received on the other side without altering the information. Each segment is then passed on to the network layer.

The network layer is responsible translates the logical addresses into their respective physical addresses and adds header data with this information to the segments received from the transport layer. The network layer passes the segments on to the data link layer. This layer is responsible for packaging the data into frames so they can be sent over the network. Verification data is added as a header to the beginning of each frame and then passed to the physical layer. The physical layer is responsible for the actual transmission using the network hardware.

On the servers side, the frames are received by the physical layer, passed to the data link layer which looks at the header and verifies the integrity of the frame. The frames are reassembled into segments and each is passed to the network layer which verifies that the segment has reached the correct node. The frame is passed on to the transport layer which reassembles the segments together into a contiguous piece of data. The data is then passed to the session layer which has kept the connection open. The session layer passes the data to the presentation layer which decompresses and decrypts the data if necessary before translating it and passing it on to the application layer. This layer formats the data and passes it on to the server software.

INCOMPLETE

Here's your solution

A reverse address resolution protocol (RARP) server maintains a table of MAC addresses and their associated IP addresses. After the RARP server receives the client's request, it consults the RARP table to find the IP address that matches the client's MAC address. The RARP server then transmits the IP address information to the client.

The Bootstrap Protocol (BOOTP) uses a central list of IP addresses and their associated devices MAC addresses to dynamically assign IP addresses to clients.

The main difference between the two protocols is that RARP requests and responses are not routable. Thus, if you wanted to use RARP to issue IP addresses, you would have to install a separate RARP server for every LAN. BOOTP, on the other hand, can traverse LANs. Furthermore, RARP is only capable of issuing an IP address to a client; BOOTP has the potential to issue additional information, such as the clients subnet mask.

Here's my answer

Both protocols receive MAC addresses and return IP addresses. The difference between the two is that RARP requests and responses are not routable whereas those of BOOTP are. In addition to that, RARP can only respond with IP addresses, BOOTP can respond with a range of additional information as well.

INCOMPLETE

Please note that the question is as follows (including the bold typeface)

What is the DIFFERENCE between BOOTP and RARP?

This means that the first two paragraphs of the solution are extra info and are irrelevent to the actual question. There are minor differences between my answer and the solutions third paragraph.

Here's the Question

When will you receive a successful ping response?

Here's the Solution

If the site is operating correctly, you should receive a response that includes multiple replies from that host.

Here's my answer

9.2 Ping is successful when the connection is reachable and four packets are successfully returned

INCOMPLETE

Here's the Question

When will you receive an unsuccessful ping response?

Here's the Solution

If the site is not operating correctly, you will receive a response indicating that the request timed out or that the host was not found. You could also receive a "request timed out" message if your workstation is not properly connected to the network, or if the network is malfunctioning.

Here's my answer

If at least one packet does not return, the ping request is unsuccessful.

INCOMPLETE

I have a network + international certification and can't believe I can't be credited for this subject!. I now realise why. The questions asked are absolutely meaningless compared to the Network + international certification. I recieved pitiful marks like everyone else and can't seem to understand why?

So I don't get to write the exam and have wasted money on a subject I should have aced whith out opening a book because the people marking these assignemnets have no clue about networking.

Thats just plain stupid!

Admittedly I didnt do assignment 2 and 3 as I thought this subject would be a walk in the park whith my current knowledge.

It just irritates me!

nickt69 Wrote:
-------------------------------------------------------
> I have a network + international certification and
> can't believe I can't be credited for this
> subject!. I now realise why. The questions asked
> are absolutely meaningless compared to the Network
> + international certification. I recieved pitiful
> marks like everyone else and can't seem to
> understand why?
>
> So I don't get to write the exam and have wasted
> money on a subject I should have aced whith out
> opening a book because the people marking these
> assignemnets have no clue about networking.
>
> Thats just plain stupid!
>
> Admittedly I didnt do assignment 2 and 3 as I
> thought this subject would be a walk in the park
> whith my current knowledge.
>
> It just irritates me!


I agree 100%, as a professional in the field myself,and as an employer of people in the field, I would be scared to hire anyone who answered the way the model answers are !!!

None of the answers are really real life solutions nor would they even help anyone out there in the field.

I think the markers of the assignments expect a word for word answer from the textbook ...

for all the textbook bashers.


Just my 2c.

Neil

To Jeethu, Varghese, I assume you are the lecturer for the module.

Satisfactory Effort, I think not. If anything, assignment 4 should be the simplest assignment compared to assignments 5 and 6. If assignment 4 is satisfactory, how the hell did I get 40 credits for assignments 5 and 6.

I don't blame these students for complaining, I don't blame them for giving in certain assignments cos they know they will they should get the relevant credits for admission to exams. You guys suck not only at setting out a paper, but also marking it. Most of these students are probably in the field and certainly know what they talking about.

I am going to have to agree with "robanaurochs".

If you have a look at the your assignment 4 answer, question 2 in tutorial 204, is not set out according to the assignment question given in tutorial 101.

The assignment question in tut 101:
"
Match each layer of the OSI-model(2.1-2.10) with the CORRECT functions(a-i) below:
2.1 Physical layer
2.2 Application layer
2.3 Adminstrative layer
2.4 Transport layer
2.5 Session layer
2.6 MAC sublayer
2.7 Network layer
2.8 Data Link layer
2.9 Presentation layer
2.10 Logical Link Control sublayer

a. Manages signalling to and from physical network connections.
b. Packages data in frames appropriate to network transmission
method.
c. Provides an interface to the network layer protocols.
d. Manages access to the physical medium.
e. Ensures accurate delivery of data.
f. Allow hosts and applications to use a common language.
g. Establishes, maintains and terminates user connections.
h. Provides the interface between applications and network for
interpreting program requests and requirements.
i. Translates network addresses into their physical counterparts.
"

I assume us students had the common sense to figure out that trying the match 10 layer to only 9 options was a mistake on the departments side. There, was no letter thereafter stating that there was an error to this question, if there even was. There was no tutorial even after the tutorial 204 came stating that there could have been some errors, which there certainly are.

Now, your tut 204 answer to question 2 states:
"
Match each layer of the OSI-model(2.1-2.10) with the correct function (a-i) below: Provide your answer by typing in only the number and the corresponding correct option, e.g. 2.1 - a

2.1 Physical layer a. Provides the interface between
applications and network for
interpreting applications' requests and
requirements.
2.2 Application layer b. Packages data in frames appropriate to
network transmission method.
2.3 Transport layer c. Provides an interface to the network
layer protocols, manages flow control
and issues requests for transmission of
data that has suffered errors.
2.4 Session layer d. Manages signalling to and from physical
network connections.
2.5 MAC sublayer e. Establishes network connections,
translats addresses into their physical
counterparts and determines routing.
2.6 Network layer f. Allows hosts and applications to use a
common language, performs data
formatting, encryption and compression.
2.7 Data Link layer g. Ensures accurate delivery of data
through flow control, segmentation and
reassembly, error correction and
acknowledgement.
2.8 Presentation layer h. Manages access to the physica medium
2.9 Logical Link Control
sublayer i. Establishes, maintains and terminates
user connections.


2.1 Physical layer d
2.2 Application layer a
2.4 Transport layer g
2.5 Session layer i
2.6 MAC sublayer h
2.7 Network layer e
2.8 Data Link layer b
2.9 Presentation layer f
2.10 Logical Link Control
sublayer c
"

Do you notice, in your answer, you have way too many errors. For instance 2.1 to 2.9, what happened to 2.10; your answer: 2.1 to 2.10, what happened to 2.3. You say it is right, when you guys marked our papers, you marked it according to your answers, not checking for sure if it is the right answer or not, or even whether the layout is right. I believe alot of students feel unfair that their answer were wrong. In actual fact, this guys "robanaurochs" answer, is absolutely correct.

Another thing, if this is how the exam paper is to set, I shudder to think who will be marking the paper, or whether it is to marked in a proper. Then when we get our results end of year, and most of us know we got right answers, but apparently marked wrong (we obviously will never know), we have to pay for remarking the paper again. I wrote the exam last year, and there were many errors with the numbering, which could have led to confusion.




Re: A Letter to the department
Posted by: Jeethu Varghese (---.unisa.ac.za) Contributor
Date: August 15, 2006 01:28PM


Dear Students

The assignments were credited on the following basis [Please refer tutorial letter 203 Page 2]:


Commendable / complete effort : 40 credits
Satisfactory Effort : 20 credits
Poor effort : 10 credits

Hope this answers your query about credit allocation for assignments. Due to the back log that happened in the assignment department we received your assignments very late and had to process it very fast which resulted in less comments than usual.

About your second point, please point out which solution you found contradicting to the text book. [Question 2 of Assignment 04 had subdivisions.

Now, there was an errata in Tutorial letter 203.Pleaser refer to that for an answer to your question regarding Assignment 05.

Please be reminded to refer your tutorial letters before contacting lecturers

Kind Regards
Lecturers