# Understanding Network Devices

Hello 👋👋

We are living in the Internet world and in this world to use internet or connected to internet , we need device which connect to the internet . That device is called Networking device .

### **List of Networking device :**

* Modem
    
* Repeater
    
* Hub
    
* Switch
    
* NIC
    
* Router
    
* Bridge
    
* Gateway
    
* Protocol
    

---

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

Modem is networking device which is convert one signal to another kind of signal .

MODEM :-MO - Modulator + DEM - Demodulator

**Modulator : Convert Computer digital signal to Wave Signal (Analogue Signal) , because wave travel in air while digital signal not , digital signal is made of 0 & 1 so how these binary data travel .**

Demodulator : Convert Received wave signal to machine understandable signal (digital signal ) .

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

Router is Networking device which work as a traffic director . which work is directs data in to his destination (where data should be go , router help in these) .

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

**Switch** : It is Networking device which work is send data to a particular device which connected to same network , switch not share data from one device to all device . It has Knowledge of MAC A

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1768783508604/3b80f20a-8d0c-4509-99a4-0096d991ef57.png align="left")

**Hub : It is networking device which work is take data from one system and send all device which connected to the network .**

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1768783471269/8783a145-638d-41b5-a252-033d5443206a.png align="left")

Real-World Analogy :

Hub is Classroom : when teacher say something then all student have to listen .

Switch is is your Whatsapp personal Chat: You send message but a particular person see your message .

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

we all are visit websites and use many type of application in which many websites and application may be malicious so here is firewall come with his superpower to protect us .

**🔥 🧱 Firewall**

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1768784441520/7f03ebc7-69e8-44d5-9dd8-efe0b501b8d6.png align="center")

**A Firewall is a network security system which exist in software or hardware that are moniter and control incoming and outgoing traffic based on predefined rules .**

**predefined rules :**

* Block all Incoming Traffic (By default , you can change these)
    
* Allow all outgoing traffic
    
* Allow specific ports
    
* Block Known Dangerous port
    

🛡️ **Security :**

In Firewall security exist here because of it 24/7 live as a security guard .

* It works 24/7 as a security guard
    
* It blocks stranger and hackers
    
* it protects from bad traffics
    
* It allows safe request
    

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

**What is a Load Balancer?**

Load balance is manager which manage traffic . Which decide to on which server user request to send .

Instead of :

> Users → 1 server (risks)
> 
> ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1768843155509/622c076d-4c6e-488b-867c-6a1cca9a4874.png align="center")

It becomes :

> Users → Load Balancer → Multiple server (risk free)

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1768843099274/23d12a71-cc13-47a3-a7ab-cc8c61c99b73.png align="center")

### why scalable systems need it?

In the real world traffic never be stable . A system which traffic laod increase and sudden spike . This is where Load Balancer came in role .

**Industory problem a Load Balancer solves :**

**problem without load balancer :**

* one server handle all requests
    
* Vertical scalling has limit (how much you upgrade a system’s CPU and RAM )
    
    ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1768843950806/fd4f1d32-4953-4343-96ce-6e8d8b34015a.png align="center")
    
* when traffic spikes, downtime
    

**How load balancer helps :**

* distribute traffic with multiple server
    
* use Horizonatal scalling (add server and remove anytime )
    
    ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1768844967709/15b737a2-998a-4075-9127-820bc357a16c.png align="center")
    

### How all these devices work together in a real-world setup?

1. user send a request a server with computer
    
2. Router directs the digital data to the modem
    
3. Modem change that digital signal to wave signal (ISP compatible signals )
    
4. tower or Fibre cable receive it wave signal
    
5. Firewalll check secirity
    
6. Load balancer pick healthy server
    
7. server response with same way
    

Amazing !🎉 I hope you learn a lot .