IBPS SO IT Officer Computer Networks Important Questions 2026 is a focused set of 15 high-yield networking questions built around the concepts that repeat most often in the Professional Knowledge paper — the OSI and TCP/IP models, IP addressing and subnetting, TCP vs UDP, application-layer protocols, routing, and network security.
Computer Networks is one of the highest-weightage subjects in the IBPS SO IT Officer Professional Knowledge section, right alongside DBMS and Operating Systems. It's also the subject where a small calculation mistake — miscounting host bits in a subnet mask, for instance — costs you a mark you actually knew how to get. This guide gives you 15 exam-style questions, several of them numerical, with full explanations and quick revision notes you can run through the night before your Mains exam.
With IBPS SO Mains 2026 scheduled for 1 November, this is the exact window to lock down subnetting speed and protocol recall. Use this list as a revision checkpoint, then move into timed topic-wise practice.
Revising All Subjects? Start With the Complete Question Set
This article goes deep on Computer Networks. If you want a broader Professional Knowledge sweep across DBMS, OS, DSA, and Cybersecurity, start with our complete 15 Most Expected Questions guide.
15 Important IBPS SO IT Officer Computer Networks Questions
Each question below targets a concept examiners test repeatedly — some purely conceptual, others calculation-based. Cover the answer, attempt it yourself, then check your logic against the explanation.
OSI & TCP/IP Reference Models (Questions 1–2)
Every networking topic sits inside one of these two models. Get the layer-by-layer mapping solid before anything else.
At which OSI layer is a MAC address added to a frame during data encapsulation?
In OSI terminology, what is the Protocol Data Unit (PDU) at the Transport Layer called?
IP Addressing & Subnetting (Questions 3–6)
Subnetting questions are the most calculation-heavy part of the Computer Networks section — and the most common place candidates lose easy marks. Practise these until they're automatic.
An IPv4 subnet is configured with the CIDR prefix /28. How many usable host addresses are available in this subnet?
A network is configured as 172.16.0.0/20. How many usable host addresses does this subnet support?
Which of the following is a valid private IPv4 address as defined by RFC 1918?
What is the subnet mask for a network using the CIDR prefix /27?
For any subnetting question, work out three numbers in order: host bits (32 − prefix), total addresses (2^host bits), and usable hosts (total − 2). Doing this in the same sequence every time removes the guesswork under exam pressure.
Transport Layer: TCP & UDP (Questions 7–9)
TCP and UDP behave very differently, and IBPS regularly tests whether you know which protocol suits which use case.
Which transport-layer protocol provides connectionless, best-effort delivery with no guarantee of ordering or reliability?
Which mechanism does TCP use to prevent a fast sender from overwhelming a slower receiver's buffer?
During TCP connection termination, why does the process typically require four segments (a 'four-way handshake') rather than the three used in connection establishment?
Application Layer Protocols (Questions 10–12)
DNS, DHCP, and HTTP/HTTPS questions test whether you know the default ports and the exact sequence each protocol follows.
Which port does DNS use by default for standard name resolution queries?
What is the correct sequence of messages in the DHCP client-server interaction, commonly remembered by the acronym DORA?
Which port does HTTPS use by default, and what underlying mechanism provides its encryption?
Routing & Network Devices (Questions 13–14)
Routing questions usually ask you to distinguish protocol types or identify what a specific device or mechanism does.
Which of the following is a link-state routing protocol that uses Dijkstra's algorithm to compute the shortest path to each destination?
Which mechanism allows multiple devices on a private network to share a single public IP address for internet access?
Network Security Basics (Question 15)
Banking IT exams lean on network security because banks handle sensitive financial traffic — know the common attack categories.
An attacker secretly intercepts and possibly alters communication between two parties who believe they are communicating directly with each other. Which attack is being described?
Topic-wise Distribution of These 15 Questions
These 15 questions deliberately spread across every major networking subtopic tested in IBPS SO IT Officer Professional Knowledge, rather than concentrating only on the OSI model.
| Topic | Questions | Concepts Covered |
|---|---|---|
| OSI & TCP/IP Reference Models | 2 | Encapsulation, PDU naming |
| IP Addressing & Subnetting | 4 | CIDR, usable hosts, private IPs, subnet masks |
| Transport Layer (TCP & UDP) | 3 | TCP vs UDP, flow control, connection termination |
| Application Layer Protocols | 3 | DNS, DHCP, HTTP/HTTPS |
| Routing & Network Devices | 2 | OSPF vs RIP, NAT |
| Network Security | 1 | Man-in-the-Middle attacks |
| Total | 15 | Complete Computer Networks Coverage |
This distribution mirrors how networking is actually weighted in previous-paper and memory-based analyses of IBPS SO IT Officer — IP addressing/subnetting and the transport layer together account for the bulk of networking questions, with application-layer protocols and security contributing a smaller but consistent share.
What Should You Revise After These 15 Questions?
Treat this list as a revision checkpoint for Computer Networks specifically. Here's the full topic checklist to work through before you consider networking "exam-ready."
OSI & TCP/IP Models
- Seven OSI layers and their functions
- Four/five-layer TCP/IP model mapping
- Encapsulation and PDU names at each layer
- Layer-wise example protocols
IP Addressing & Subnetting
- IPv4 address classes (A, B, C)
- CIDR notation and subnet mask conversion
- Calculating usable hosts and number of subnets
- Public vs private IP ranges
- IPv6 basics and address format
Transport Layer
- TCP three-way handshake and four-way termination
- TCP flow control and congestion control basics
- UDP characteristics and use cases
- Port numbers for common protocols
Application Layer Protocols
- DNS resolution process and record types
- DHCP (DORA process)
- HTTP vs HTTPS, common status codes
- FTP, SMTP, and other common protocols and their ports
Routing
- Distance-vector vs link-state routing
- RIP, OSPF, and BGP basics
- Static vs dynamic routing
- ARP and its role in address resolution
Network Devices & NAT
- Hub, switch, router, and gateway — what each actually does
- NAT and its types (static, dynamic, PAT)
- VLANs and basic segmentation concepts
Network Security
- Firewalls, IDS, and IPS
- Common attacks: MITM, DoS/DDoS, ARP spoofing, phishing
- VPN basics
- SSL/TLS and certificate-based trust
Knowing the definition of subnetting and correctly calculating usable hosts for a specific CIDR value are two different skills. The same is true for TCP/UDP theory and protocol port numbers — pair every concept you revise with at least one worked numerical example.
These 15 Questions Are Not Enough — Practice at Exam Level
Networking questions in the actual Mains exam often combine two concepts in one scenario — a subnetting question that also asks you to identify the correct broadcast address, or a protocol question that expects you to know both the port number and the underlying mechanism. The only way to get fast and accurate at this is timed, varied practice.
Revise → Practice → Analyse → Revise Weak Areas → Repeat
Attempt an IBPS SO IT Officer Mock Test
Move from concept revision to exam-style practice with MockSensei's free, timed IBPS SO IT Officer mock tests — including topic-wise Computer Networks questions.
Final Takeaway
These 15 questions are best used as a quick revision checkpoint for the Computer Networks portion of Professional Knowledge, ideally alongside the complete 15 Most Expected Questions guide covering DBMS, OS, DSA, and Cybersecurity. With Mains on 1 November, the priority now is coverage and speed — revise every subtopic above, drill subnetting calculations until they're automatic, and get comfortable spotting the concept being tested within the first few seconds of reading a question.
Revise the concepts. Practise the calculations. Analyse your mistakes. Then practise under exam conditions.