In simple words …Network connects devices locally while the Internet connects Networks Globally
{Internet is a large system of Networks}

Now let’s understand the Networking Devices—>

What is a Modem ?

Modem is a device which converts ISP(Internet Service Provider) signals into digital data basically It talks to Internet Service Provider and brings Internet into your house. now you think why we need this device the problem is that the signals which are coming from Internet Service Providers(ISP) transmit data using various signal formats (electrical, optical, radio) which must be converted into digital data for computers. hence the Modem is used to convert it .
Now you may be confused that I don’t have the any Modem at my home but still i have the Internet Access ? so let me clear this, Your phone itself is a MODEM because smartphone contains a cellular modem chip (hardware), built into the processor.

There are Two working process of this devices:

• Modulator→ Converts Digital signals into ISP signals

• Demodulator→ Converts ISP signals into Digital signals

What is a Router ?

Now Using modem we get the Internet access at home , we have multiple devices at home like Phone, Laptop, TV etc. so how to connect these devices to internet hence the ROUTER is come in networking arena .
Router is a device that shares the Internet from Modem to multiple devices Using IP addresses. To assign IP addresses router use DHCP and NAT.

Router act a brain of the local network.

• DHCP=Dynamic Host Configuration Protocol

It creates private IP addresses and automatically assigns them to devices in network.

Like:

1. Phone → 192.168.1.2

2. Laptop → 192.168.1.3

3. TV → 192.168.1.4

• NAT=Network Address Translation

It keeps a translation table and allows many devices to use one public IP.

Difference between Modem and Router

• Modem act as a Translator —> Brings Internet into your Networks

• Router act as a Manager —> Distribute and manages internet inside your network

Switch vs Hub: how local networks actually work?

In a network, Hubs and Switches act as the central "meeting point" for all your devices in local Area network(LAN), where both are used to connect multiple devices in Local Area Network, without this devices we have to plug every computer directly into every other computer using cables.

1. HUB : It is a basic networking device that sends incoming data to All connected Devices
   EX.. If 4 computers (Computer A, B, C and D) are connected to Hub and Computer A sends data to Computer C.
   HUB will receive the data from A and send it to ALL ports (B, C and D) , here the problem is
   → Waste of Bandwidth
   → Security risk
   → Slow Network
   → Collisions(Data clash)

To solve this problem, The Modern device SWITCH is entered……

2. SWITCH : Switch is an Intelligent device as compare to HUB, It sends incoming data only to the Destination Device [Intended device]

It follows the principal→> “Serve Who Wants“

EX.. If 4 computers (Computer A, B, C and D) are connected to Hub and Computer A sends data to Computer C.
SWITCH will receive the data from A and send it directly to C , here the problem is solved
→ It is Fast
→ Secure
→ Efficient

What is a Firewall ?

In any device or in any Network, Security is the Digital Lock and ‘Guard’ for your information so, here FIREWALL is act as a Security guard that controls what network traffic is allowed or blocked.

A firewall is a hardware or software security device that monitors and filters incoming and outgoing network traffic based on predefined rules.

Follows rules like :

• Allow HTTPS

• Allow HTTP

• Block Foreign IPs

• Block Suspicious ports

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

“Load-Balancer”, Obviously as a name it balances the Load of Server, It is a system that distributes incoming traffic across multiple servers so that no single server becomes overloaded. When thousands of users try to access your website at once at that time single server became overloaded…

It tells, which servers are busy and which are free, then sends the user to the best available one.

The Conclusion

If you are in Software sector then you may have question “Why should I care about hardware/network devices if I write code?”
Even though modem, router, switch, firewall, load balancer are hardware, software runs THROUGH them. Now let’s visualize this devices using AI

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