COMP247 Data Communications Assignment 1 Solution - University Name

This document presents a comprehensive solution to a COMP247 Data Communications assignment. The solution addresses questions on subnetting, including converting slash notation to dotted-decimal subnet masks and calculating the maximum number of hosts for various networks. It also includes an analysis of Internet Relay Chat (IRC) and Domain Name System (DNS) protocols, detailing their architectures, functionalities, and the protocols they utilize, such as TCP and UDP. The assignment incorporates supporting arguments and references, adhering to IEEE referencing style, and provides a bibliography of relevant sources. The document offers a detailed exploration of network layer concepts and protocols within the context of a data communications course.

Running head: COMP247 DATA COMMUNICATIONS
COMP247 Data Communications
Name of the Student
Name of the University
Author’s Note

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Answer to Question 1:
a. The equivalent subnet mask for the following slash notation in dotted decimal
notation is as follows:
i. /21 –
= 255.255.248.0
ii. /13 –
= 255.248.0.0
iii. /29 –
= 255.255.255.248
b. The maximum number of hosts that can be addressed on the following networks are
given below:
i. /19 – 255.255.224.0
= 8192 – 2
=8190 hosts
ii. /30 – 255.255.255.252
= 4 – 2
= 2 hosts
iii. /23 – 255.255.254.0
= 512 – 2
= 510 hosts
c. Checking legal subnet address and its corresponding slash notation form are given
below:
i. 255.255.224.0 –
Binary form - 11111111.11111111.11100000.00000000
Notation - /19

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ii. 255.128.0.0 –
Binary form – 11111111.10000000.00000000.00000000
Notation - /9
iii. 255.252.255.0 –
Binary form – 11111111.11111100. 11111111.00000000
Notation - invalid
iv. 255.255.255.254 –
Binary form - 11111111.11111111.11111111.11111110
Notation - /31
Answer to Question 2:
Internet Relay Chat (IRC) –
[A]. IRC is being used for the facilitation of communication through text format using its
application layers’ protocols. A network model for the client’s server has been used to work
on chat process of its clients of whom mostly are various programs of computer that are
installed by its users through various web based applications or system so that they could be
run through third parties’ servers or locally. A communication has to be initiated through chat
server so that messages could be transmitted to clients. The basic design also facilitates group
also known channels. Private messages could also be sent in one-one format with features of
files as well as data transfer.
[B]. Each operating system which has support system for internet accessing does supports
client software. Being open protocol, it allows users for sharing of files with IRC clients
along with exchanging messages.

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[C]. For the purpose of handling messages along with their guaranteed delivery, TCP
protocol has to be used by IRC. This also gives a guarantee of no losing of any files or data
during the process of transfer.
[D]. TCP protocol has to be selected by protocol designer like TLS (transport Layer Security)
or Secure socket layers (SSL) which could be used for encrypting all the data that are
exchanged between users. Messages are sent in plain text format between users which helps
clients in group chats through channels. These channels could also be expanded through
connecting with different IRC servers through which clients could chat.
[E]. For the purpose of connection through other servers, client’s server architecture has to be
used, after which IRC network could be formed. IRCnet, EFnet, DAL and Undernet being
examples for IRC networks.
[F]. IRC networks are usually defined by groups of various interconnected network. IRC
network can be formed using single server system. The design is of three spanning
architecture in which each server that are connected acts like central node of remaining
networks. This protocol will not support any direct communication from any of its servers
instead, it relays communication through all its servers that are connected in network.
Domain Name System (DNS) –
[A]. DNS maps website names with corresponding IP address that are assigned to websites.
Majority of web browsing and activity in internet is directly relied on DNS so that it could
return information required by remote host connected with various websites. DNS mapping is
maintained through hierarchy of authorities all over the internet. It includes governments,
access providers, universities, various enterprises and organisation having individual IP
address range along with various domain names that are being assigned to them. For

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convenience of mapping, URLs of websites are made around domain name that are linked
with various servers so that clients request could be taken.
[B]. DNS servers uses client server models so that communication could be enabled while
working on UDP protocols which is to be used for communication of transport layer through
port 53. It acts as layer protocol for applications as it defines as to how messages would be
passed. It also goes on defining meaning, syntax, rules and various types of messages and as
to how it would be determined when and how DNS responds and sends these messages.
[C]. The DNS has any different features from other protocol like restriction of any direct
interaction through the DNS. Names translation of various services is given by DNS. Queries
from both outside as well as inside domain are responded through DNS servers. Queries
related to address and name from any sender which is from different outer domain is given
very authoritatively while giving all the necessary information’s, but if it is received via inner
domain, the proposal is then forwarded to another server which is managed through different
internet service providers.
[D]. The different messages in domain naming systems are received, being sent over to UDP
port no 53 before acknowledging from receiving systems. Because it uses UDP, message
deliveries are not guaranteed because of this, any system could be obligated in using TCP
port53.
UDP though is not as reliable as other but has an advantage of speed over TCP
protocol supporting multiple clients because of absence of connection state. For reducing
resolving time, DNS protocol has been designed using UDP. For the purpose of increasing
and enhancing security, some extra layer of protection could be added in this protocol which
would also help it's speed.

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Because of small requests of DNS, it could be easily fitted with UDP segment. It
eliminates any need for three way handshakes which was needed for transmitting data thus
saving a lot of time. The UDP could be used with different variation by DNS protocol such as
resending and timeouts at basic application layer which would definitely increase its
reliability.
[E]. For the purpose of transmitting data, client’s server architectures are used by DNS.
[F]. Address resolution or naming of websites in the internet is done through the application
of DNS. The translation of domain naming to its IP address is done through the help of DNS.
The DNS having its own various network cannot translate particular domain and for this it
asks various servers till a correct IP address is being returned.

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Bibliography
[1] J. Deng, "On the Politeness Strategies in Chinese Internet Relay Chat
Communication", Open Journal of Modern Linguistics, vol. 06, no. 04, pp. 293-301, 2016.
Available: 10.4236/ojml.2016.64030.
[2] A. Belloni, G. Lopomo and S. Wang, "Resource Allocation Under Demand Uncertainty
and Private Information", Management Science, vol. 63, no. 12, pp. 4219-4235, 2017.
Available: 10.1287/mnsc.2016.2574.