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Introduced in the late 1950s for the purpose to serve the U.S. military radar system, commonly known as SAGE (Semi-Automatic Ground Environment), computer networking is the field that has great opportunities for the candidates who are willing to pursue it as a career option. The primary objective of introducing networking is to enable the nodes to share relevant resources across different platforms.
In the field of computer networks, exchanging data through computing devices are performed using data links or connections between nodes. These connections or the data links are fixed over cable media which includes wires, optic cables, wireless media like Wi-Fi. With the increasing demand in the market, networking over a period of time, have gained a lot of momentum and is a must-required resource in the market.
A network is a set of devices connected to each other using a physical transmission medium.
Example: A Computer Network is a group of computers connected with each other to communicate and share information and resources like hardware, data, and software across each other.
In a network, nodes are used to connect two or more networks.
Two or more computers are connected directly by an optical fiber or any other cable. A node is a point where a connection established. It is a network component which is used to send, receive and forward the electronic information.
A device connected to a network is also termed as Node. Lets consider that in a network there are 2 computers, 2 printers, and a server are connected, then we can say that there are five nodes on the network.
image source: Nodes
Network Topology is a physical layout of the computer network and it defines how the computers, devices, cables etc are connected to each other.
The router is a network device which connects two or more network segments. The router is used to transfer information from the source to destination.
Routers send the information in terms of data packets and when these data packets are forwarded from one router to another router then the router reads the network address in the packets and identifies the destination network.
Open System Interconnection, the name itself suggest that it is a reference model which defines how applications can communicate with each other over a networking system.
It also helps to understand the relationship between networks and defines the process of communication in a network.
Given below are the seven layers of OSI Reference Models:
Hub is least expensive, least intelligent and least complicated of the three.
Switches work similarly like Hubs but in a more efficient manner.
The router is smartest and most complicated out of these three. It comes in all shapes and sizes. Routers are similar like little computers dedicated for routing network traffic
In a Network, Hub is a common connection point for devices connected to the network. Hub contains multiple ports and is used to connect segments of LAN
Switch is a device in a network which forwards packets in a network
Routers are located at gateway and forwards data packets
Ans: The most widely used and available protocol is TCP/IP i.e. Transmission Control Protocol and Internet Protocol. TCP/IP specifies how data should be packaged, transmitted and routed in their end to end data communication.
There are four layers as shown in the below diagram:
image source: TCP/IP
Given below is a brief explanation of each layer:
HTTP is HyperText Transfer Protocol and it is responsible for web content. Many web pages are using HTTP to transmit the web content and allow the display and navigation of HyperText.
It is the primary protocol and port used here is TCP port 80.
HTTPS is a Secure HTTP. HTTPS is used for secure communication over a computer network. HTTPS provides authentication of websites which prevents unwanted attacks.
In a bi-directional communication, HTTPS protocol encrypts the communication so that tampering of the data gets avoided. With the help of a SSL certificate, it verifies if the requested server connection is a valid connection or not. HTTPS uses TCP with port 443.
Common factors in TCP and UDP:
TCP stands for Transmission Control Protocol
UDP is stands for User Datagram Protocol or Universal Datagram Protocol
Once the connection is setup, data can be sent bi-directional i.e. TCP is a connection oriented protocol
UDP is connectionless, simple protocol. Using UDP, messages are sent as packets
The speed of TCP is slower than UDP
UDP is faster compared to TCP
TCP is used for the application where time is not critical part of data transmission
UDP is suitable for the applications which require fast transmission of data and time is crucial in this case.
TCP transmission occurs in a sequential manner
UDP transmission also occurs in a sequential manner but it does not maintain the same sequence when it reaches the destination
It is heavy weight connection
It is lightweight transport layer
TCP tracks the data sent to ensure no data loss during data transmission
UDP does not ensure whether receiver receives packets are not. If packets are misses then they are just lost
Firewall is a network security system that is used to protect computer networks from unauthorized access. It prevents malicious access from outside to the computer network. A firewall can also be built to grant limited access to the outside users.
The firewall consists of a hardware device, software program or a combined configuration of both. All the messages that route through the Firewall are examined by specific security criteria and the messages which meet the criteria are successfully traversed through the network or else those messages are blocked.
image source: Firewall
Firewalls can be installed just like any other computer software and later can be customized as per the need and have some control over the access and security features. “
Windows Firewall” is an inbuilt Microsoft Windows application which comes along with the operating system. This “Windows Firewall” also helps to prevent viruses, worms etc.
Domain Name Server (DNS), in a non-professional language and we can call it as Internet’s phone book. All the public IP addresses and their hostnames are stored in the DNS and later it translates into a corresponding IP address.
For a human being, it is easy to remember and recognize the domain name, however, the computer is a machine that does not understand the human language and they only understand the language of IP addresses for data transfer.
There is a “Central Registry” where all the domain names are stored and it gets updated on a periodic basis. All the internet service providers and different host companies usually interact with this central registry to get the updated DNS details.
For Example: When you type a website www.softwaretestinghelp.com, then your internet service provider looks for the DNS associated with this domain name and translates this website command into a machine language – IP address – 18.104.22.168 (note that, this is imaginary IP address and not the actual IP for the given website) so that you will get redirected to the appropriate destination.
This is shortly explained in the below diagram:
image source: DNS
In a Computer Network, different computers are organized in different methods and these methods are – Domains and Workgroups. Usually, computers which run on the home network belong to a Workgroup. However, computers which are running on an office network or any workplace network belong to the Domain.
All computers are peers and no computer has control over another computer
Network admin uses one or more computer as a server and provide all accesses, security permission to all other computers in a network
In a Workgroup, each computer maintains their own database
The domain is a form of a computer network in which computers, printers, and user accounts are registered in a central database.
Each computer has their own authentication rule for every user account
It has centralized authentication servers which set the rule of authentication
Each computer has set of user account. If user has account on that computer then only user able to access the computer
If user has an account in a domain then user can login to any computer in a domain
Workgroup does not bind to any security permission or does not require any password
Domain user has to provide security credentials whenever they are accessing the domain network
Computer settings need to change manually for each computer in a Workgroup
In a domain, changes made in one computer automatically made same changes to all other computers in a network
All computers must be on same local area network
In a domain, computers can be on a different local network
In a Workgroup, there can be only 20 computers connected
In a domain, thousands of computers can be connected
For data transmission, IP addresses are required and even DNS uses IP addresses to route to the correct website. It means without the knowledge of correct and actual IP addresses it is not possible to identify the physical location of the network.
Proxy Servers prevent external users who are unauthorized to access such IP addresses of the internal network. The Proxy Server makes the computer network virtually invisible to the external users.
image source: Proxy Server
An IP address has 4 sets (octets) of numbers each with a value up to 255.
For Example, the range of the home or commercial connection started primarily between 190 x or 10 x. IP classes are differentiated based on the number of hosts it supports on a single network. If IP classes support more networks then very few IP addresses are available for each network.
There are three types of IP classes and are based on the first octet of IP addresses which are classified as Class A, B or C. If the first octet begins with 0 bit then it is of type Class A.
Class A type has a range up to 127.x.x.x (except 127.0.0.1). If it starts with bits 10 then it belongs to Class B. Class B having a range from 128.x to 191.x. IP class belongs to Class C if octet starts with bits 110. Class C has a range from 192.x to 223.x.
IP address 127.0.0.1, is reserved for loopback or local host connections. These networks are usually reserved for the biggest customers or some of the original members of the Internet. To identify any connection issue, the initial step is to ping the server and check if it is responding.
If there is no response from the server then there are various causes like the network is down or the cable needs to be replaced or network card is not in a good condition. 127.0.0.1 is a loopback connection on the Network Interface Card (NIC) and if you are able to ping this server successfully, then it means that the hardware is in a good shape and condition.
127.0.0.1 and local host are the same things in most of the computer network functioning.
NIC stands for Network Interface Card. It is also known as Network Adapter or Ethernet Card. It is in the form of add-in card and is installed in a computer so that the computer can be connected to a network.
Each NIC has a MAC address which helps in identifying the computer on a network.
In a computer network, to enable data transmission from one computer to another, the network devices send messages in the form of packets. These packets are then added with the IP header by OSI reference model layer.
The Data Link Layer encapsulates each packet in a frame which contains the hardware address of the source and the destination computer. If a destination computer is on the remote network then the frames are routed through a gateway or router to the destination computer.
The terminologies Internet, Intranet, and Extranet are used to define how the applications in the network can be accessed. They use similar TCP/IP technology but differ in terms of access levels for each user inside the network and outside the network.
Internet: Applications are accessed by anyone from any location using the web.
Intranet: It allows limited access to the users in the same organization.
Extranet: External users are allowed or provided with access to use the network application of the organization.
VPN is the Virtual Private Network and is built on the Internet as a private wide area network. Internet-based VPNs are less expensive and can be connected from anywhere in the world.
VPNs are used to connect offices remotely and are less expensive when compared to WAN connections. VPNs are used for secure transactions and confidential data can be transferred between multiple offices. VPN keeps company information secure against any potential intrusion.
image source: VPN
Given below are the 3 types of VPNs:
#1) Access VPN: Access VPNs provides connectivity to the mobile users and telecommuters. It is an alternative option for dial-up connections or ISDN connections. It provides low-cost solutions and a wide range of connectivity.
#2) Intranet VPN: They are useful for connecting remote offices using shared infrastructure with the same policy as a private network.
#3) Extranet VPN: Using shared infrastructure over an intranet, suppliers, customers, and partners are connected using dedicated connections.
Ipconfig stands for Internet Protocol Configuration and this command is used on Microsoft Windows to view and configure the network interface.
The command ipconfig is useful for displaying all TCP/IP network summary information currently available on a network. It also helps to modify the DHCP protocol and DNS setting.
Ifconfig (Interface Configuration) is a command that is used on Linux, Mac, and UNIX operating system. It is used to configure, control the TCP/IP network interface parameters from CLI i.e. Command Line Interface. It allows you to see the IP addresses of these network interfaces.
DHCP stands for Dynamic Host Configuration Protocol and it automatically assigns IP addresses to the network devices. It completely removes the process of manual allocation of IP addresses and reduces the errors caused due to this.
This entire process is centralized so that TCP/IP configuration can also be completed from a central location. DHCP has “pool of IP addresses” from which it allocates the IP address to the network devices. DHCP cannot recognize if any device is configured manually and assigned with the same IP address from the DHCP pool.
In this situation, it throws “IP address conflict” error.
image source: DHCP DHCP environment requires DHCP servers to set-up the TCP/IP configuration. These servers then assign, release and renew the IP addresses as there might be a chance that network devices can leave the network and some of them can join back to the network.
SNMP stands for Simple Network Management Protocol. It is a network protocol used for collecting organizing and exchanging information between network devices. SNMP is widely used in network management for configuring network devices like switches, hubs, routers, printers, servers.
SNMP consists of the below components:
The below diagram shows how these components are connected with each other in the SNMP architecture:
image source: SNMP
SNMP is a part of TCP/IP suite. There are 3 main versions of SNMP which include SNMPv1, SNMPv2, and SNMPv3.
There are 4 major types of network.
Lets take a look at each of them in detail.
There are some other types of network as well:
Through Transmission the data gets transferred from source to destination (Only one way). It is treated as the physical movement of data.
Communication means the process of sending and receiving data between two media (data is transferred between source and destination in both ways).
OSI model stands for Open System Interconnection It is a framework which guides the applications how they can communicate in a network.
OSI model has seven layers. They are listed below,
Size of the Network is defined as the geographic area and the number of computers covered in it. Based on the size of the network they are classified as below,
Based on the size of the Network they are classified as below,
There are three types of internet connections. They are listed below
Below are few important terms we need to know in networking
Network engineers are known to build and design effective computer networking systems and alternatives. They are also responsible to install software applications that usually make the connections between the organizational services with the client machines at a faster rate. In the world of digitalization, the scope of job opportunities in the field of networking has increased in recent years. Jobs such as network engineering posts is something that you should be looking into.
A fresher in the field of networking is offered about 35,000 to 45,000 dollars per annum, while the experienced ones are offered with a hike of 30 percent and above, depending on their previous withdrawn salary. An experienced candidate can withdraw up to 114,000 to 125,000 dollars per annum based on the skills and expertise he or she has.
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