A Modem (Modulator–Demodulator) is a networking device that connects a local network to the Internet by converting computer digital signals into ISP transmission signals (fiber/DSL/cable) and converting incoming signals back into digital form.
👉 Short Interview Answer:
A modem connects the network to the ISP and provides Internet access.
📍 Network Flow:
Laptop → Router → Modem → ISP → Internet
| Type | Price |
| Basic DSL | ₹1,200 – ₹2,500 |
| Fiber ONT | ₹2,000 – ₹4,000 |
| Modem + WiFi | ₹3,500 – ₹7,000 |
| Enterprise | ₹10,000+ |
📌 Many ISPs provide modem free or rental.
TP-Link • D-Link • Netgear • Huawei • Nokia
A Hub is a Layer-1 networking device that connects multiple computers and sends incoming data to all connected ports without checking destination.
👉 A hub broadcasts data to all devices.
Hubs are obsolete today → replaced by switches.
Used earlier in:
Computer A sends data → Hub sends to ALL computers
➡ Creates collisions & slow network
₹800 – ₹2,000 (rarely available)
D-Link • TP-Link • Netgear
A Switch is a Layer-2 (or Layer-3) device that connects devices in a LAN and sends data only to the correct device using MAC address.
👉 Unlike hub, switch sends data intelligently.
Banks • Offices • Colleges • Hospitals • ISPs • Data Centers
| Type | Price |
| 8-Port | ₹1,200 – ₹2,500 |
| 24-Port | ₹3,000 – ₹6,000 |
| Managed L2 | ₹8,000 – ₹25,000 |
| Layer 3 | ₹30,000 – ₹2,00,000+ |
| Core Switch | ₹3,00,000+ |
Cisco • Juniper • Huawei • Aruba • Dell
A Router is a Layer-3 device that connects multiple networks and forwards data using IP addresses.
👉 Router connects LAN to Internet.
Phone connects to Wi-Fi → Router assigns IP → Sends request to Google → Returns response
📌 Without router → No Internet
| Type | Price |
| Home | ₹1,500 – ₹5,000 |
| SMB | ₹10,000 – ₹40,000 |
| Enterprise | ₹1L – ₹10L+ |
Home: TP-Link, D-Link, Netgear
Office: MikroTik, Ubiquiti, Cisco
ISP: Juniper, Huawei, Nokia
A Firewall is a security device that monitors and filters network traffic based on rules and protects networks from unauthorized access.
👉 Firewall allows safe traffic and blocks harmful traffic.
Banks • Schools • Offices • Government • Home
| Type | Price |
| OS Firewall | Free |
| Antivirus | ₹800 – ₹2,500 |
| Small Office | ₹8,000 – ₹25,000 |
| Business | ₹40,000 – ₹2,50,000 |
| Enterprise NGFW | ₹5,00,000+ |
Palo Alto • Fortinet • Cisco • Sophos • Check Point
An Access Point (AP) connects wireless devices to a wired network using radio signals.
👉 Provides Wi-Fi connectivity.
Offices • Colleges • Hotels • Airports • Homes
| Type | Price |
| Home | ₹2,000 – ₹4,000 |
| Dual-Band | ₹3,500 – ₹8,000 |
| Enterprise | ₹8,000 – ₹40,000 |
| Outdoor | ₹12,000 – ₹70,000+ |
TP-Link • Ubiquiti • Cisco • Aruba • Huawei
Enterprise networking leader (offices, campuses)
ISP backbone & telecom networks
Advanced cybersecurity & firewalls
| Vendor | Role |
| Cisco | Enterprise networking |
| Juniper | Internet backbone routing |
| Palo Alto | Network security |
