# Understanding Network Devices

## What is a Modem and how it connects your network to the internet?

> A modem is a device which acts as a mediator between the ISP (Internet Service Provider) and the user.
> 
> The ISP provides internet access, and without a modem, the ISP cannot connect your device to the internet.
> 
> A modem change( Modulate and De-modulate ) the signals received from the ISP into digital data that our devices can understand.
> 
> ISPs can be Jio, Airtel, BSNL, etc.

## What is a Router and how it directs traffic?

> Router is the device which decide The data packet will be served to reach destination IP it is the 3rd layer of computer network
> 
> These look the destination IP address by looking into routing table
> 
> It can also understood as It decide where to forward The received data packet next
> 
> ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1769840902526/e582a11c-91d0-4614-9848-b25796b7b70c.png align="center")

## Switch vs Hub: how local networks actually work?

### Switch

> A **switch** is a networking device that **connects multiple devices within the same network and sends data only to the intended device**.
> 
> Switch Find the destination mac(Media Access Control address) address by looking into Mac table

## Hub

> A **hub** is a basic networking device that **provide data to all the devices connected to it** .
> 
> ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1769842124138/62e39866-947f-4865-af06-074098e6c942.png align="center")

| **Feature** | **Router** | **Switch** | **Hub** |
| --- | --- | --- | --- |
| User | Ip address | Mac address | No address |
| Data delivery | Best Path | Correct path | All device |

### What is a Firewall and why security lives here?

> A firewall may be a hardware or a software Which provide security to a System from untrusted source
> 
> If it is a hardware It should be placed in between Internet and router To protect the private device From Public devices

### What is a Load Balancer and why scalable systems need it?

> For software which used to Divide the number of requests Coming from Large number of Users Into different servers so that It can manage and response Each and every request Easily
> 
> ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1769845134835/e108270d-fb22-489a-ad4f-215c0d8cfd86.png align="center")
> 
> 1. The response time of the server build degrees When large number of users is interacting
>     
> 2. The server will not crash when A high load
>     
> 3. User experience will increased By the load balancer
>     

## End-to-end network architecture for a web application

> As we have seen different Network devices Let us combine the whole and make a complete Wave architecture from this To understand it clearly
> 
> ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1769846361152/27f3433f-0829-43f2-9583-c92fe6d92778.png align="center")

**This article provides an overview of key networking devices and their roles in connecting and securing networks. It explains how modems facilitate internet connectivity from ISPs like Jio and Airtel, how routers manage data traffic, and the differences between switches and hubs in local networks. It covers the importance of firewalls for security and load balancers for scalable systems. Finally, it outlines an end-to-end network architecture for a web application.**