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Networking for IT Officer

What the subject covers, the key topics, how it has been asked, common mistakes and a two-week plan.

  • 9 min read
  • 7 topic groups
  • 48 terms in the glossary
  • 10 topics

IBPS publishes no official syllabus; this list is based on previous papers.

What the subject covers

Networking is about how data gets from one computer to another:

Quick revision

Tap a term to open its definition.

Key topics

Layered models

OSI, 7 layers, the TCP/IP model, PDU names and transmission modes.
OSI, 7 layers, top to bottom
LayerJob
Applicationnot stated
PresentationFormat, encryption
SessionDialogue control
TransportEnd-to-end delivery, ports
NetworkLogical addressing, routing
Data LinkFraming, MAC addresses, error detection
PhysicalBits on the medium

TCP/IP model

Application, Transport, Internet, Network Access (link). Know which OSI layers map to which.

PDU names
LayerPDU
PhysicalBits
Data linkFrame
NetworkPacket
TransportSegment for TCP / datagram for UDP
ApplicationData/message
Transmission modes
ModeDirection
SimplexOne way
Half duplexBoth ways, one at a time
Full duplexBoth ways at once

Network layer: IP addressing

IPv4 classes, private ranges, subnetting and CIDR, IPv6, helper protocols and routing.

IPv4

32 bits, dotted decimal.

IPv4 classful ranges (first octet)
ClassFirst octetDefault mask
A1–126255.0.0.0 (/8)
B128–191255.255.0.0 (/16)
C192–223255.255.255.0 (/24)
D224–239Multicast
E240–255Reserved

127.x.x.x is loopback.

Private ranges

10.0.0.0/8, 172.16.0.0/12 (172.16–172.31), 192.168.0.0/16.

Also know APIPA, 169.254.x.x.

Subnets (subnetting and CIDR)

Borrowing n host bits gives 2ⁿ subnets. Older books use 2ⁿ − 2 subnets (no subnet zero); if both 2ⁿ and 2ⁿ − 2 appear in the options, the question follows the old classful rule.

Usable hosts per subnet

With h host bits left, each subnet has 2ʰ − 2 usable hosts: the network and broadcast addresses are reserved.

IPv6

128 bits, written in hex in 8 groups; :: shortens one run of zero groups.

There's no broadcast (multicast and anycast instead) and the base header is a fixed 40 bytes.

ARP

ARP finds the MAC address for an IP on the local network; RARP did the reverse.

ICMP

ICMP carries error and diagnostic messages, used by ping and traceroute.

NAT

NAT translates private addresses to a public one, so many devices share one public IP and their internal addresses stay hidden.

DHCP

DHCP hands out IP settings automatically.

Routing: distance vector, link state, path vector
TypeProtocolHow
Distance vectorRIPHop count, maximum 15 hops, Bellman-Ford
Link stateOSPFDijkstra's shortest path
Path vectorBGPBetween autonomous systems on the internet

Routing is static vs dynamic.

Transport layer

TCP vs UDP, the 3-way handshake, flow and congestion control, and ports.
TCP vs UDP
ComparedTCPUDP
TypeConnection-oriented and reliableConnectionless, no guarantees, low overhead
Used fornot statedDNS queries, DHCP, streaming and VoIP

3-way handshake

SYN, SYN-ACK, ACK.

TCP is reliable through a 3-way handshake, sequence numbers, acknowledgements and retransmission.

TCP control: flow control with a sliding window; congestion control with slow start and congestion avoidance.

Ports
PortProtocol
20/21FTP
22SSH
23Telnet
25SMTP
53DNS
67/68DHCP
80HTTP
110POP3
143IMAP
161SNMP
443HTTPS

Application layer

HTTP/HTTPS, DNS, email (SMTP, POP3, IMAP) and FTP.

HTTP methods: GET, POST, PUT, DELETE.

HTTP status code classes
ClassMeaning
1xxInformational
2xxSuccess
3xxRedirect
4xxClient error
5xxServer error

HTTPS

HTTP is stateless (cookies add state); HTTPS is HTTP over TLS.

DNS

Turns names into IP addresses.

Know record types A, AAAA, MX, CNAME, NS, and recursive vs iterative queries.

Email: SMTP, POP3, IMAP
ProtocolWhat it does
SMTPSends mail and runs over TCP
POP3Usually downloads mail and removes it from the server
IMAPKeeps mail on the server and syncs folders and read status across devices

FTP

Separate control and data connections.

Transfer modes: stream, block, compressed.

Delays and performance

Transmission and propagation delay, store-and-forward, bandwidth and throughput.

Transmission delay

Packet size ÷ link rate (L/R).

Propagation delay

Distance ÷ signal speed.

Store-and-forward

Each router must receive the whole packet before sending it on. Through N routers there are N + 1 links, so the transmission delay alone is (N + 1) × L/R.

Also know bandwidth vs throughput, and the bandwidth-delay product.

Devices and topologies

Devices by layer, collision and broadcast domains, topologies, LAN, MAN and WAN.
Devices by layer
DeviceLayerNote
Hub and repeaterLayer 1One collision domain
Switch and bridgeLayer 2Each switch port is its own collision domain; switches can mirror a port for monitoring
RouterLayer 3Separates broadcast domains
Gatewaynot statedConnects different protocols

Topologies: bus, star, ring, mesh (n(n−1)/2 links for full mesh), tree, hybrid. Also know LAN, MAN and WAN.

How it is asked

Official

From the official IBPS documents

These are the facts about the format from the official IBPS documents:

  • Professional Knowledge in the Mains has 50 questions for 100 marks in 40 minutes (2 marks each, −0.50 for a wrong answer).
  • Each question has five options. In IBPS's sample, the fifth is "Other than those given as options".

Sources: IBPS official notification CRP SPL-XVI (1 Jul 2026); IBPS Information Handout, Online Main Exam CRP SPL-XVI, “notification §D; handout, Professional Knowledge sample question”

Not official

From memory-based papers (unofficial)

IBPS doesn't publish past papers. Based on memory-based papers shared by candidates (unofficial) for two previous IT Officer Mains exams (January 2023 and December 2024; possibly incomplete), networking questions were of three kinds:

  • Address arithmetic: the class and first-octet range of an address, how many networks a class has, picking a private address, and the subnet mask needed for a given number of subnets.
  • Protocol facts in one line: which transport protocol a service uses, which protocol is bit-oriented, what ARP and NAT do, a feature of IMAP, FTP transfer modes, what a traceroute option does, PDU names per layer, and matching OSI layers to their jobs.
  • Devices, standards and calculations: the maximum length of a 100BASE-TX segment, trunk VLANs, which device supports port mirroring, full duplex, and a store-and-forward delay formula.

Firewall types and network attacks also came up; they are covered under Information and cyber security. We don't give a number of networking questions, because IBPS publishes no weightage.

Common mistakes

Our suggestion

Two-week study plan

A suggestion. Adjust it to your own pace.

  1. Days 1–2

    OSI and TCP/IP, PDUs, transmission modes

    Practice: Write each layer's job, protocols and device from memory

  2. Days 3–4

    Data link: framing, error detection/correction, flow control, Ethernet, CSMA/CD/CA, VLANs

    Practice: Work out CRC and Hamming examples by hand

  3. Days 5–7

    IPv4 classes, private ranges, subnetting, CIDR, IPv6

    Practice: 20 subnetting problems a day, timed

  4. Day 8

    ARP, ICMP, NAT, DHCP, routing protocols

    Practice: Compare RIP, OSPF and BGP in a table

  5. Days 9–10

    TCP vs UDP, handshake, windows, congestion, ports

    Practice: Port-number flashcards until you get them all right

  6. Day 11

    HTTP/HTTPS, DNS, email protocols, FTP

    Practice: Trace what happens when you open a web page, step by step

  7. Day 12

    Delays, throughput, devices, topologies

    Practice: Delay calculations; collision vs broadcast domains

  8. Days 13–14

    Mixed revision

    Practice: Timed set of 25 questions in 20 minutes; review every wrong answer

Show the plan as a table
Two-week study plan
DaysFocusPractice
1–2OSI and TCP/IP, PDUs, transmission modesWrite each layer's job, protocols and device from memory
3–4Data link: framing, error detection/correction, flow control, Ethernet, CSMA/CD/CA, VLANsWork out CRC and Hamming examples by hand
5–7IPv4 classes, private ranges, subnetting, CIDR, IPv620 subnetting problems a day, timed
8ARP, ICMP, NAT, DHCP, routing protocolsCompare RIP, OSPF and BGP in a table
9–10TCP vs UDP, handshake, windows, congestion, portsPort-number flashcards until you get them all right
11HTTP/HTTPS, DNS, email protocols, FTPTrace what happens when you open a web page, step by step
12Delays, throughput, devices, topologiesDelay calculations; collision vs broadcast domains
13–14Mixed revisionTimed set of 25 questions in 20 minutes; review every wrong answer

Glossary A–Z

48 terms

Symbols

A

  • APIPASee Private ranges.
  • ARPARP finds the MAC address for an IP on the local network; RARP did the reverse.

B

  • BGPSee Routing: distance vector, link state, path vector.

C

  • CIDRSee Subnets (subnetting and CIDR).
  • CRCSee Framing and error control: detect vs correct.
  • CSMA/CASee Media access: CSMA/CD vs CSMA/CA.
  • CSMA/CDSee Media access: CSMA/CD vs CSMA/CA.

D

  • DHCPDHCP hands out IP settings automatically.
  • DNSTurns names into IP addresses.

F

  • FTPSeparate control and data connections.
  • Full duplexSee Transmission modes.

G

H

  • Half duplexSee Transmission modes.
  • Hamming codeSee Framing and error control: detect vs correct.
  • HTTPSee HTTPS.
  • HTTPSHTTP is stateless (cookies add state); HTTPS is HTTP over TLS.
  • HubSee Devices by layer.

I

  • ICMPICMP carries error and diagnostic messages, used by ping and traceroute.
  • IMAPSee Email: SMTP, POP3, IMAP.
  • IPv432 bits, dotted decimal.
  • IPv6128 bits, written in hex in 8 groups; :: shortens one run of zero groups.

L

  • LoopbackSee IPv4 classful ranges (first octet).

M

N

  • NATNAT translates private addresses to a public one, so many devices share one public IP and their internal addresses stay hidden.

O

  • OSI modelSee OSI, 7 layers, top to bottom.
  • OSPFSee Routing: distance vector, link state, path vector.

P

R

  • RARPSee ARP.
  • RIPSee Routing: distance vector, link state, path vector.
  • RouterSee Devices by layer.

S

  • SimplexSee Transmission modes.
  • SMTPSee Email: SMTP, POP3, IMAP.
  • Store-and-forwardEach router must receive the whole packet before sending it on. Through N routers there are N + 1 links, so the transmission delay alone is (N + 1) × L/R.
  • Subnets (subnetting and CIDR)Borrowing n host bits gives 2ⁿ subnets. Older books use 2ⁿ − 2 subnets (no subnet zero); if both 2ⁿ and 2ⁿ − 2 appear in the options, the question follows the old classful rule.
  • SwitchSee Devices by layer.

T

  • TCPSee TCP vs UDP.
  • TCP/IP modelApplication, Transport, Internet, Network Access (link). Know which OSI layers map to which.
  • Transmission delayPacket size ÷ link rate (L/R).
  • Trunk linkA trunk link carries several VLANs, tagged with IEEE 802.1Q.

U

  • UDPSee TCP vs UDP.
  • Usable hosts per subnetWith h host bits left, each subnet has 2ʰ − 2 usable hosts: the network and broadcast addresses are reserved.

V

  • VLANA VLAN splits one switch into separate broadcast domains.
Not official · based on previous papers

Networking topics

10 topics. Practice questions: 0 so far, 2-mark questions coming soon.

Networking FAQ

Is subnetting asked in IBPS SO IT Officer?

Subnetting and IP-class questions appear in memory-based papers of previous Mains exams shared by candidates (unofficial). IBPS doesn't publish a syllabus or weightage, but subnetting is quick to master and the answers are exact, so it's worth practising.

Do I need to memorise port numbers?

Learn the common ones (FTP, SSH, Telnet, SMTP, DNS, DHCP, HTTP, POP3, IMAP, SNMP, HTTPS). They take little time and come up in one-line questions.

OSI or TCP/IP: which model should I study?

Both. Know the 7 OSI layers in order with their jobs, the TCP/IP layers, and how the two map onto each other.

How deep should I go into routing?

Know the main types (static vs dynamic; distance vector, link state, path vector), the algorithm behind each (Bellman-Ford, Dijkstra) and the common protocols (RIP, OSPF, BGP) with their key limits, such as RIP's 15 hops.

How many networking questions come in the Mains?

IBPS doesn't say. Professional Knowledge has 50 questions in total for 100 marks; the split across subjects isn't published.

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