Frequently Asked Questions

Network is defined as a set of devices connected to each other using a physical transmission medium.

For 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. In a network, nodes are used to connect two or more networks.

Network topology is a physical layout of the computer network and it defines how the computers, devices, cables, etc are connected to each other.

Open System Interconnection, the name itself suggests that it is a reference model that 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.

Hub

Hub is least expensive, least intelligent and least complicated of the three. It broadcast all data to every port which may cause serious security and reliability concern.

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

Switches work similarly like Hubs but in a more efficient manner. It creates connections dynamically and provides information only to the requesting port.

Switch is a device in a network which forwards packets in a network.

Router

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.

Routers are located at gateway and forwards data packets

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.

Common factors in TCP and UDP are:

TCP and UDP are the most widely used protocols that are built on the top of the IP protocol.

Both protocols TCP and UDP are used to send bits of data over the Internet, which is also known as ‘packets’.

When packets are transferred using either TCP or UDP, it is sent to an IP address. These packets are traversed through routers to the destination.

Domain Name Server (DNS), in a non-professional language and we can call it an 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 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 – 151.144.210.59 (note that, this is the imaginary IP address and not the actual IP for the given website) so that you will get redirected to the appropriate destination.

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. It makes the computer network virtually invisible to external users.

Proxy Server also maintains the list of blacklisted websites so that the internal user is automatically prevented from getting easily infected by viruses, worms, etc.

IP address 127.0.0.1, is reserved for loopback or localhost 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 the network card is not in 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 localhost are the same things in most of the computer network functioning.

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 the OSI reference model layer.

The Data Link Layer encapsulates each packet in a frame that 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.

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.

Given below are the 3 types of VPN’s:

Access VPN: Access VPN’s provide connectivity to 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.

Intranet VPN: They are useful for connecting remote offices using shared infrastructure with the same policy as a private network.

Extranet VPN: Using shared infrastructure over an intranet, suppliers, customers, and partners are connected using dedicated connections.

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 the TCP/IP configuration can also be completed from a central location. DHCP has a “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.

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.

There are 4 major types of networks.

Let’s take a look at each of them in detail.

Personal Area Network (PAN): It is the smallest and basic network type that is often used at home. It is a connection between the computer and another device such as phone, printer, modem tablets, etc.

Local Area Network (LAN): LAN is used in small offices and Internet cafes to connect a small group of computers to each other. Usually, they are used to transfer a file or for playing the game in a network.

Metropolitan Area Network (MAN): It is a powerful network type than LAN. The area covered by MAN is a small town, city, etc. A huge server is used to cover such a large span of area for connection.

Wide Area Network (WAN): It is more complex than LAN and covers a large span of the area typically a large physical distance. The Internet is the largest WAN which is spread across the world. WAN is not owned by any single organization but it has distributed ownership.

There are some other types of the network as well:

Storage Area Network (SAN)
System Area Network (SAN)
Enterprise Private Network (EPN)
Passive Optical Local Area Network (POLAN)

OSI model stands for Open System Interconnection It is a framework that guides the applications on how they can communicate in a network.

OSI model has seven layers. They are listed below,

Physical Layer: Deals with transmission and reception of unstructured data through a physical medium.

Data Link Layer: Helps in transferring error-free data frames between nodes.

Network Layer: Decides the physical path that should be taken by the data as per the network conditions.

Transport Layer: Ensures that the messages are delivered in sequence and without any loss or duplication.

Session Layer: Helps in establishing a session between processes of different stations.

Presentation Layer: Formats the data as per the need and presents the same to the Application layer.

Application Layer: Serves as the mediator between Users and processes of applications.

There are three types of Internet connections. They are listed below:

Broadband Connection: This type of connection gives continuous high-speed Internet. In this type, if we log off from the Internet for any reason then there is no need to log in again. For Example, Modems of cables, Fibres, wireless connection, satellite connection, etc.

Wi-Fi: It is a wireless Internet connection between the devices. It uses radio waves to connect to the devices or gadgets.

WiMAX: It is the most advanced type of Internet connection which is more featured than Wi-Fi. It is nothing but a high-speed and advanced type of broadband connection.

ASCII stands for American Standard Code for Information Interchange.

In data transmission, if the sender sends any data frame to the receiver then the receiver should send the acknowledgment to the sender. The receiver will temporarily delay (waits for the network layer to send the next data packet) the acknowledgment and hooks it to the next outgoing data frame, this process is called Piggybacking.

The main characteristics of networking are mentioned below:

Topology: This deals with how the computers or nodes are arranged in the network. The computers are arranged physically or logically.

Protocols: Deals with the process of how computers communicate with one another.

Medium: This is nothing but the medium used by computers for communication.

Network Topology is nothing but the physical or logical way in which the devices (like nodes, links, and computers) of a network are arranged. Physical Topology means the actual place where the elements of a network are located.

Logical Topology deals with the flow of data over the networks. A link is used to connect more than two devices of a network. And more than two links located nearby form a topology.

Network topologies are classified as below:

a) Bus Topology: In Bus Topology, all the devices of the network are connected to a common cable (also called as the backbone). As the devices are connected to a single cable, it is also termed as Linear Bus Topology.

The advantage of bus topology is that it can be installed easily. And the disadvantage is that if the backbone cable breaks then the whole network will be down.

b) Star Topology: In Star Topology, there is a central controller or hub to which every node or device is connected through a cable. In this topology, the devices are not linked to each other. If a device needs to communicate with the other, then it has to send the signal or data to the central hub. And then the hub sends the same data to the destination device.

The advantage of the star topology is that if a link breaks then only that particular link is affected. The whole network remains undisturbed. The main disadvantage of the star topology is that all the devices of the network are dependent on a single point (hub). If the central hub gets failed, then the whole network gets down.

c) Ring Topology: In Ring Topology, each device of the network is connected to two other devices on either side which in turn forms a loop. Data or Signal in ring topology flow only in a single direction from one device to another and reaches the destination node.

The advantage of ring topology is that it can be installed easily. Adding or deleting devices to the network is also easy. The main disadvantage of ring topology is the data flows only in one direction. And a break at a node in the network can affect the whole network.

d) Mesh Topology: In a Mesh Topology, each device of the network is connected to all other devices of the network. Mesh Topology uses Routing and Flooding techniques for data transmission.

Brouter or Bridge Router is a device that acts as both a bridge and a router. As a bridge, it forwards data between the networks. And as a router, it routes the data to specified systems within a network.

VPN stands for Virtual Private Network. With the help of a VPN, remote users can securely connect to the organization’s network. Corporate companies, educational institutions, government offices, etc use this VPN.