Networking is the practice of connecting two or more computing devices so they can share resources and exchange data. In the context of SBI PO Computer Awareness, "networking" is not about memorising every technical RFC — it is about knowing which layer does what, which device lives where, and which protocol serves which purpose.
Think of a network like a postal system. Every device has an address (IP address). The postal worker who decides the best route for your letter is the router. The local post office that knows every address on your street is the switch. The person who just shouts the message to the entire neighbourhood without caring who needs it is the hub. The rules that define how letters must be formatted, addressed, and stamped are the protocols.
Networks are classified by their geographic span:
The two dominant reference models you must know cold are the OSI model (7 layers, theoretical reference) and the TCP/IP model (4 layers, practical implementation). SBI PO questions pivot between both — and they love asking which layer maps to which layer across the two models.
| Type | Range | Speed | Example | |------|-------|-------|---------| | PAN | ~10 m | Low | Bluetooth, USB | | LAN | Building | High | Office Ethernet | | MAN | City | Medium-High | City Wi-Fi grid | | WAN | Global | Variable | Internet, MPLS |
The OSI (Open Systems Interconnection) model is a conceptual framework. Layer numbers matter: questions ask "which layer does X?" and the answer is always a specific number and name.
| Layer | Number | Key Function | Devices/Protocols | |-------|--------|-------------|-------------------| | Physical | 1 | Transmits raw bits over physical medium | Hub, Repeater, Cables | | Data Link | 2 | Error detection, MAC addressing, frames | Switch, Bridge, NIC | | Network | 3 | Logical addressing, routing | Router, IP | | Transport | 4 | End-to-end communication, segmentation | TCP, UDP | | Session | 5 | Establishes, manages, terminates sessions | NetBIOS, PPTP | | Presentation | 6 | Data translation, encryption, compression | SSL/TLS, JPEG, ASCII | | Application | 7 | User-facing services | HTTP, FTP, SMTP, DNS |
Memory anchor: "Please Do Not Throw Sausage Pizza Away" — Physical, Data Link, Network, Transport, Session, Presentation, Application.
The TCP/IP model is what the actual internet runs on. Exam questions frequently ask which OSI layer maps to which TCP/IP layer.
| TCP/IP Layer | Maps to OSI Layers | |-------------|-------------------| | Network Interface (Link) | Physical + Data Link (1 & 2) | | Internet | Network (3) | | Transport | Transport (4) | | Application | Session + Presentation + Application (5, 6, 7) |
Look — the critical mapping for SBI PO is: Internet Layer (TCP/IP) = Network Layer (OSI). This appears verbatim in PYQs.
Bus: All devices share a single backbone cable. Failure of the backbone kills the entire network. Cheap but not fault-tolerant.
Star: All devices connect to a central hub or switch. Most common in modern LANs. A single device failure doesn't affect others — only the central device failure takes down the network. Easy to troubleshoot.
Ring: Each device connects to exactly two others, forming a loop. Data travels in one direction (or both in dual-ring). Token Ring is the classic protocol. One break in the ring disrupts communication.
Mesh: Every device connects to every other device. Highly fault-tolerant. Used in WANs and critical infrastructure. Expensive — number of links = n(n-1)/2 for a full mesh.
Tree (Hierarchical): A hybrid of star and bus. Nodes are arranged in a hierarchy. Used in large corporate networks.
Hybrid: Combination of two or more topologies.
| Device | OSI Layer | Function | |--------|-----------|----------| | Hub | Layer 1 — Physical | Broadcasts signals to all ports, no intelligence | | Switch | Layer 2 — Data Link | Forwards frames based on MAC address table | | Router | Layer 3 — Network | Routes packets based on IP address; connects different networks | | Gateway | Layer 4–7 | Protocol translation between different network architectures | | Bridge | Layer 2 — Data Link | Connects two LAN segments, filters by MAC | | Repeater | Layer 1 — Physical | Amplifies/regenerates signal over long distances |
File Transfer:
Web & Email:
Network Support:
| Class | First Octet Range | Default Subnet Mask | Typical Use | |-------|-------------------|---------------------|-------------| | A | 1–126 | 255.0.0.0 (/8) | Very large networks | | B | 128–191 | 255.255.0.0 (/16) | Medium networks | | C | 192–223 | 255.255.255.0 (/24) | Small networks | | D | 224–239 | — | Multicasting | | E | 240–255 | — | Reserved/Research |
Class C gives you 256 addresses per network (0–255), with the first 24 bits for network identification.
From weakest to strongest: WEP → WPA → WPA2 → WPA3
Cat 5e cable: 100 metres maximum for standard Ethernet (10BASE-T, 100BASE-TX, 1000BASE-T). Beyond this, signal attenuation degrades performance. Repeaters or switches extend range.
Lock three device-layer pairs in 10 seconds with this pattern: Hub=1, Switch=2, Router=3. Remember "HSR" → "Half Speed Runner" — Hub (slowest, dumbest), Switch (smarter), Router (routes, smartest of the three). Standard method: reading all 7 layers and scanning = 40s. Pattern recall: under 5s. These three pairs account for ~80% of SBI PO device-layer questions.
TCP/IP has 4 layers; OSI has 7. The collapse pattern: TCP/IP Network Interface = OSI layers 1+2; TCP/IP Internet = OSI layer 3; TCP/IP Transport = OSI layer 4; TCP/IP Application = OSI layers 5+6+7. Write it as fractions: NI=1+2, I=3, T=4, A=5+6+7. When asked "which TCP/IP layer is equivalent to OSI Network Layer?" — I=3, answer is Internet Layer. Standard cross-reference scan: 30s. This mapping recall: 4s.
WEP (3 letters) → WPA (3 letters) → WPA2 (4 chars) → WPA3 (4 chars). The number suffix tells you the generation: no number is older, 2 is second-gen, 3 is current. "Higher number = safer" applies perfectly here. When any option shows WPA3, it is the most secure answer — zero exceptions in current exam context. Eliminates 3 wrong options in 3 seconds.
Class A: 1 octet is 255, rest are 0 → 255.0.0.0. Class B: 2 octets are 255 → 255.255.0.0. Class C: 3 octets are 255 → 255.255.255.0. "Class letter number = number of 255 octets." A=1, B=2, C=3. Applying this: Class C subnet mask in 2 seconds flat vs. trying to recall it cold (8–12 seconds with uncertainty).
FTP = basic transfer (plaintext), SFTP = SSH-secured transfer, TFTP = Trivial (UDP, no auth). Any question asking "secure file transfer" → eliminate FTP (plaintext) and TFTP (no authentication) immediately. SFTP is the only option with SSH encryption. Two-step elimination in under 5 seconds replaces needing to recall port numbers or protocol details. Note: HTTP is not a file-transfer protocol — eliminate it first if it appears.
When you see a networking question in SBI PO, run this mental decision tree in under 10 seconds:
Step 1 — Identify the question type:
Step 2 — Apply elimination: If the correct answer is not immediately clear, eliminate the obviously wrong options first. In most networking MCQs, two options are from different categories entirely — they can be cut in 3 seconds.
Step 3 — Confirm with one anchor fact: Each correct answer should trigger one verifiable fact. If it doesn't feel anchored, re-check. Don't second-guess a confident recall.
Target: networking questions solved in 30–45 seconds each.
Why this question: IP class subnet masks appear regularly and students confuse Class A with Class C.
Solving path: Class C = 3 octets of 255. Write 255.255.255.0. Done in 4 seconds. Option A (255.0.0.0) is Class A — trap for students who mix letter-to-octet count. Option D (255.255.255.255) is a host route — no valid default class uses it.
Why this question: OSI layer functions — the most common computer awareness question type in banking exams, appearing in virtually every year.
Solving path: "Routing packets between different networks" = logical addressing function = Layer 3 = Network Layer. Data Link Layer (Layer 2) handles same-network framing. Transport Layer (Layer 4) handles end-to-end reliability. Session Layer (Layer 5) manages connections — not routing. Anchor: Router = Layer 3 = Network Layer. Confirmed in 6 seconds.
Why this question: TCP/IP to OSI mapping is a direct exam favourite — tests whether you know both models, not just one.
Solving path: TCP/IP has 4 layers. The Internet Layer handles IP addressing and routing — same job as OSI's Network Layer (Layer 3). Apply the collapse formula: I=3. Network Interface Layer maps to OSI Layers 1+2 (not Layer 3). Transport and Application are one-to-one matches. Answer: Internet Layer.
Why this question: WiFi security protocol hierarchy tests rote knowledge but elimination makes it mechanical.
Solving path: Hierarchy: WEP (broken) → WPA → WPA2 → WPA3 (current, strongest). WPA3 uses SAE and enhanced AES. Eliminate WEP immediately (publicly broken protocol). WPA and WPA2 are superseded. WPA3 is the answer. Two-step elimination: 5 seconds total.
Why this question: SFTP vs FTP is a classic "which is secure?" question that tests protocol knowledge under time pressure.
Solving path: Eliminate HTTP first — it's a web protocol, not file transfer. Eliminate FTP — transmits in plaintext. Eliminate TFTP — Trivial FTP has no authentication. SFTP uses SSH encryption for both authentication and data transfer. One elimination round = 4 seconds to the correct answer.
Why this question: Topology identification is consistently tested — star topology is the most common in modern LANs.
Solving path: "Central hub or switch" is the defining feature of Star Topology. Bus has a single shared backbone — no central device. Ring connects each node to two others in a loop — no central device. Mesh connects all nodes to all others — no single centre. The moment you see "central device," the answer is Star.
Why this question: Device-layer mapping is the highest-frequency single-fact question in banking computer sections.
Solving path: Hub = Layer 1 (Physical) — it blindly repeats electrical signals with no processing. Switch = Layer 2 (Data Link) — reads MAC addresses. Router = Layer 3 (Network) — reads IP addresses. Gateway = Layer 4–7. The question says "Physical Layer" — only Hub fits. Anchor: Hub broadcasts everything, knows nothing. Answer confirmed in 5 seconds.
Confusing Hub and Switch layer assignments. Hub is Layer 1 (Physical) and Switch is Layer 2 (Data Link). Students often reverse these because both "connect devices." The differentiator: Hub has zero intelligence about data, Switch reads MAC addresses. If you remember that MAC addressing belongs to Layer 2, Switch falls into place automatically.
Mixing OSI and TCP/IP layer names on cross-model questions. When a question asks for the TCP/IP equivalent of OSI's Network Layer, writing "Network Layer" is wrong — the TCP/IP name is "Internet Layer." Always check which model the question is asking about before answering.
Selecting WPA2 as the most secure wireless protocol. WPA2 was the gold standard until WPA3 was introduced. Modern exam questions specifically test whether you know WPA3 exists and supersedes WPA2. If WPA3 is an option, it is the answer.
Choosing FTP for "secure file transfer." FTP is the insecure version. SFTP (SSH-based) is secure. FTPS (FTP over SSL) is another secure variant you may see — but the exam typically contrasts plain FTP against SFTP. The word "secure" in the question = SFTP.
Applying Class A subnet mask to Class C or vice versa. Students sometimes recall "255.0.0.0" for all classes because it appears first in memory. Use the octet-count rule strictly: the class letter position in the alphabet (A=1, B=2, C=3) equals the number of 255 octets in the mask.
Treating 100-metre Ethernet limit as approximate. The Cat 5e maximum is exactly 100 metres (not 150, not 200). This number is precise in specifications and exams test for it exactly. 150 metres and 200 metres are distractor options designed to catch guessers.