Networking and Data Communication PYQs – Computer, SSC & Railway

Answer: Option 2 — VoLTE transmits voice calls as data packets over the LTE network using IP Multimedia Subsystem (IMS)
VoLTE (Voice over LTE) carries the voice itself as IP data packets over the 4G LTE network, handled by the IP Multimedia Subsystem (IMS).
That gives HD voice, much faster call setup and voice with data at the same time — but only on a VoLTE-capable handset and network.
Revision note — VoLTE and mobile telecom generations
• Before VoLTE a 4G phone had to drop to the 2G/3G circuit-switched network to make a call (CSFB, Circuit Switched Fallback), breaking the data session. VoLTE keeps everything packet-switched.
• IMS is the core that sets up and manages the call; SIP is the signalling protocol, and the wideband AMR-WB codec is what is marketed as HD voice.
• VoWiFi (Wi-Fi calling) carries the same IMS call over a Wi-Fi link instead of the cellular network — a companion service, not VoLTE itself.
• Generations: 1G analogue voice, 2G digital voice and SMS (GSM), 3G mobile data, 4G LTE all-IP broadband, 5G very high speed and low latency.
• Circuit switching reserves one dedicated path for the whole call; packet switching splits the data into packets routed independently. LTE is entirely packet-switched.
• India's telecom regulator is TRAI, set up in 1997, and the Telecommunications Act, 2023 replaced the colonial Indian Telegraph Act, 1885.
Do not mix these up
• VoLTE vs VoWiFi — VoLTE runs over the cellular LTE network; VoWiFi runs over a Wi-Fi connection.
• VoLTE vs ordinary internet calling apps — VoLTE is a carrier-grade service with priority inside the operator's network; an app is just data traffic.
• Circuit-switched vs packet-switched — a reserved end-to-end path against independently routed packets.
Also asked from this topic: the standard for wired LANs (IEEE 802.3; Wi-Fi is 802.11); what a MAC address identifies (a NIC at the data link layer); the law replaced in 2023 (Telegraph Act, 1885).

Topic: Computer Networks - LAN Components
ALAN (Local Area Network)connects multiple devices within a limited area for resource sharing.
Devices connect to the network medium through a specialized hardware adapter.
Network Interface Card (NIC)is the adapter that:
• Provides physical connection to network
• Converts data into network signals
• Has unique MAC address for identification
Answer: Option 3 → Network Interface Card

Topic: LAN (Local Area Network)
Definition:LAN connects devices within a limited area like a building, office, or campus.
Key Characteristics:
• Covers small geographical area (room/building)
• High-speed data transfer
• Connects computers, printers via wired/wireless
Analysis of Options:
Option 1: ✓ Correct - LAN connects local computers in same building
Option 2: ✗ Bluetooth is separate wireless technology, not LAN
Option 3: ✗ Satellite phones use satellite networks, not LAN
Option 4: ✗ Global servers use WAN (Wide Area Network), not LAN

Topic:IEEE Standards for Networks
IEEE 802.3→ Ethernet standard for wired LANs
IEEE 802.11 → Wireless LAN (Wi-Fi)
IEEE 802.16 → WiMAX (Wireless MAN)
IEEE 802.15 → Wireless PAN (Bluetooth)
Answer: Option 1 → IEEE 802.3

Topic: LAN (Local Area Network)
LAN is a computer network that connects devices within a limited area.
Key characteristics:
• Covers small geographical area (office, school, building)
• High-speed data transfer
• Owned and managed by single organization
Other options:
Option 2 refers to ASCII/Unicode encoding
Option 3 refers to DVD/Blu-ray disc
Option 4 refers to CD/DVD drive
Answer: Option 1 → A network covering a small geographical area like an office or school