CUSTOMER_CODE
SMUDE
DIVISION_CODE
SMUDE
EVENT_CODE
SMUAPR15
ASSESSMENT_CODE MCA3050_SMUAPR15
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
18330
QUESTION_TEXT
What are the difference between Analog and Digital Network?
SCHEME OF
EVALUATION
Differences between Analog and Digital Networks:
[Any FIVE. TWO Marks Each. 2 Marks x 5 = 10 Marks]
1.Feature: Signal.
Analog Characteristics: Continuously variable in both amplitude and
frequency.
Digital Characteristics: Discrete signal represented as either changes
in voltage or changes in light levels.
2.Feature: Traffic Measurement.
Analog Characteristics: Hz (for example, a telephone channel is
4KHz).
Digital Characteristics: Bits per second (for example, a T-1 line
carries 1.544 Mbps and an E-1 line transports 2.048 Mbps).
3.Feature: Bandwidth
Analog Characteristics: Low bandwidth (4KHz), which means low
data transmission rates because of limited channel bandwidth.
Digital Characteristics: High-bandwidth that can support high-speed
data and emerging applications that involve video and multimedia.
4.Feature: Network Capacity.
Analog Characteristics: Low; one conversation per telephone
channel.
Digital Characteristics: High; multiplexers enable multiple
conversations to share a communication channel and hence to
achieve greater transaction efficiencies.
5.Feature: Network Manageability.
Analog Characteristics: Poor; a lot of labor is needed for network
maintenance and control because dumb analog devices do not
provide management information streams that allow the device to be
remotely managed.
Digital Characteristics: Good; smart devices produce alerts, alarms,
traffic statistics and performance measurements and technicians at a
Network Control Center (NCC) or Network Operations Center
(NOC) can remotely monitor and manage the various network
elements.
6.Feature: Power requirements
Analog Characteristics: High because the signal contains a wide
range of frequencies and amplitudes.
Digital Characteristics: Low because only two discrete signals – the
one and the zero – needs to be transmitted.
7.Feature: Security
Analog Characteristics: Poor; when you tap into an analog circuit;
you hear the voice stream in its native form, and it is difficult to
detect an intrusion.
Digital Characteristics: Good; encryption can be used.
8.Feature: Error rates.
Analog Characteristics: High; 10 -5 bits (that is 1 in 100,000 bits) is
guaranteed to have an error.
Digital Characteristics: Low; with twisted-pair, 10 -7 bits (that is 1 in
10 million bits per second) will have an error, with satellite 10 -9 (that
is 1 in 1 billion bits per second) will have an error, 10 -11 (that is 1 in
10 trillion bits per second) will have an error.
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
73695
QUESTION_TEXT
Explain the various fields present in LAP – D frame format.
SCHEME OF
EVALUATION
1. Flag: The flag field is a one-octet field that delimits.
2. Address: The address field is a two-octet field.
3. Control: The address field is a one or two octet field that
identifies the frame type.
4. Information: The information field is a variable size field with
a max of 260 octet comprising upper layer of information.
5. Frame Check Sequence: The FCS field is a two octet field.
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
73696
QUESTION_TEXT
Name the fields present in OSPF header
1.
2.
3.
SCHEME OF EVALUATION
4.
5.
6.
Version Number.
Packet Length
Router id
Checksum
Authentication Type
Authentication Data
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
73697
QUESTION_TEXT Briefly explain the different Queue Management Algorithms
SCHEME OF
EVALUATION
1. Different Queue Management Algorithms:
FIFO Algorithm: The heart of this algorithm lies in that if overload
occurs, packets are placed onto a single common queue and
retrieved from it according to other order in which they arrived- that
is first in first out. In all packet switching devices, the FIFO algorithm
is used by default. (2 marks)
2. Priority Queuing: These types of algorithms are popular in many
areas of computing – for example multitasking operating systems,
where certain applications must priority over others. These
algorithms are also used for priority queuing, when some classes of
traffic must have priority over others. The priority-queuing is based
on dividing all network traffic into a small number of classes and
assigning some numeric characteristics, known as priority to each
class. (2 marks)
3. Weighted Queuing: This algorithm is developed to provide
certain minimum bandwidth to all classes of traffic, or at least to
guarantee observations of some requirements to delays. Class
weight is the percentage of the total bandwidth of the resource that
is guaranteed to this class of traffic. Like priority queuing, weighted
queuing requires the division of the traffic into several classes. For
each class, a separate queue is created. However in weighted
queuing each queue is assigned the percentage of the resource
bandwidth guaranteed to this class under conditions of resource
overload rather than a specific priority. For input flow, role of
resource is played by the processor, and for the output flow, this
role is played by the output interface. (3 marks)
4. Hybrid Algorithm of Queuing: Both of the two algorithms
(priority and weighted) has some advantages and drawbacks. A
hybrid algorithm is trying to find a compromise between those two
algorithms. The most popular type of such an algorithm uses one
priority queue and serves all other queues according to the
weighted algorithm. Usually priority queues are used for real-time
traffic and other queues are used for elastic traffic of several classes.
Each class of elastic traffic get some guaranteed minimum of the
bandwidth during congestion periods. This minimum is calculated as
percentage of the bandwidth remaining after serving the priority
traffic. However, it is necessary to limit the priority traffic somehow
to prevent it from consuming the entire bandwidth of the resource.
(3 marks)
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
125314
QUESTION_TEXT
What are the Different layers in internet model? Explain each one.
There are four layers in internet model. (2 Marks)
SCHEME OF
EVALUATION
1.
Host-to-network/link layer
2.
Internet layer
3.
Transport layer
4.
Application model
Explanation on each layer (Each carry 2 Marks)
Host-to-network/link layer: It is a interface between hosts and
transmission links. It supports all standard and proprietary protocols
Internet layer: The main responsibility of this layer is to permit
hosts to inject packets into any network and have travel
autonomously to the destination.
Transport layer: It is designed to allow peer entities on the source
and destination hosts to carry on a conversation.
Application layer: This contains all higher level protocols such as
DNS, HTTP, FTP, SMTP etc.
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
125317
QUESTION_TEXT Define Proxy Server. Explain different types of Proxy.
1.
2.
SCHEME OF
EVALUATION
3.
4.
In computer networks, a proxy server is a server (a computer
system or an application) that acts as an intermediary for requests
from clients seeking resources from other servers. A client
connects to the proxy server, requesting some service, such as
file, connection, web page, or other resource available from a
different server. The proxy server evaluates the request as a way
to simplify and control their complexity. (2 marks)
Different types of proxy: Forward Proxy: Forward Proxies are
Proxies where the client server names the largest server to
connect to. Forward “roxies are able to retrieve from a wide
range of resources. (2 marks)
Open Proxy: An Open Proxy is a forwarding proxy server that
is accessible by any Internet user. (1 mark)
Reverse Proxy: A Reverse Proxy (or surrogate) is a proxy
server that appear to clients to be an ordinary server. Requests
are forwarded to one or more origin servers which handle the
request. The response is returned as if it came directly from the
proxy server. Reverse Proxies are installed in the neighborhood
of one or more web servers. All traffic coming from the Internet
and with a destination of one of the neighborhood’s web server
goes through the proxy server. The use of “reverse” originates its
counterpart “forward proxy” since the reverse proxy sits closer to
the web server and servers only a restricted set of websites.
Figure below shows different types of proxies: (5 marks)
(Diagram not required)