Basics of Computer Networking
05/08/2019 Department of CS&IT, University of Poonch Rawalakot
Basics of Computer Networking
→ Open System:
A system which is connected with a network and is ready for the
communication.
→ Closed system:
A system which is not connected with a network and can’t be
communicated with.
→ Computer Network:
A computer network is an interconnection of multiple devices, generally
named as “Hosts” connected using multiple paths for the purpose of
resource sharing and sending/receiving data or media .
05/08/2019 Department of CS&IT, University of Poonch Rawalakot
OSI (reference model)
→ OSI:
OSI stands for Open Systems Interconnection. It is a reference model
that specifies standards for communications protocols and also the
functionalities of each layer.
OSI model has seven layers listed below:-
→ Application Layer
→ Presentation Layer
→ Session Layer
→ Transport Layer
→ Network Layer
→ Datalink Layer
→ Physical Layer
05/08/2019 Department of CS&IT, University of Poonch Rawalakot
Protocol
→ Protocol:
A protocol is the set of rules or algorithms which define the way how two
entities can communicate across the network.
There are different protocol defined at each layer of the OSI model, few of
which are TCP, UDP, ARP, IP, DHCP, FTP and so on.
05/08/2019 Department of CS&IT, University of Poonch Rawalakot
UNIQUE IDENTIFIERS OF NETWORK
→ Host name:
Each device in the network is associated with a unique device name known
as Hostname.
To display the hostname of a device, open command prompt, type
“hostname” and press enter.
05/08/2019 Department of CS&IT, University of Poonch Rawalakot
UNIQUE IDENTIFIERS OF NETWORK
→ IP Address (Internet Protocol address):
IP address is also known as logical address. It is the network address of the
system across the network.
Internet Assigned Numbers Authority (IANA) assigns IPV4 address as a
unique identifier for each device on the Internet.
Length of the IP address is 32-bits. (Hence we have 232 IP addresses
available.)
To display the IP address of the device, open command prompt, type
“ipconfig” and press enter.
05/08/2019 Department of CS&IT, University of Poonch Rawalakot
UNIQUE IDENTIFIERS OF NETWORK
→ MAC Address (Media Access Control address):
MAC address is also known as physical address, is the unique identifier of
each host and is associated with the NIC (Network Interface Card).
MAC address is assigned to the NIC at the time of manufacturing.
Length of the MAC address is 48 bits.
To display the MAC address of the device, open command prompt, type
“ipconfig/all” and press enter.
05/08/2019 Department of CS&IT, University of Poonch Rawalakot
UNIQUE IDENTIFIERS OF NETWORK
→ Port:
Port can be referred as a logical channel through which data can be
sent/received to an application.
Any host may have multiple applications running, and each of this
application is identified using the port number on which they are running.
Port number is a 16-bit integer, hence we have 216 ports available.
To lists all the ports being used, open command prompt, type “netstat -a”
and press enter.
→ Socket:
The unique combination of IP address and Port number together are
termed as Socket.
05/08/2019 Department of CS&IT, University of Poonch Rawalakot
Few more concepts
→ DNS Server:
DNS stands for Domain Name system.
DNS is basically a server which translates web addresses or URL into their
corresponding IP addresses.
To find the IP address of any domain , open command prompt, type
“nslookup www.abc.com” and press enter.
→ ARP:
ARP stands for Address Resolution Protocol.
It is used to convert the IP address to its corresponding Physical Address.
ARP is used by the Data Link Layer.
05/08/2019 Department of CS&IT, University of Poonch Rawalakot
