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Network Engineer key topics and quick reference

Updated 15 September 2026 · 2 min read

Engineering questions assume a solid layer of facts and then build on it. The reference tables here collect those facts, from where each protocol sits in the OSI model to how far each cable type can carry traffic. The notes below explain which facts matter most for design work and how they connect.

How this guide was made

Written for this site with AI assistance, then checked automatically before publishing. The topic table, sample questions, worked examples and study plan are generated from this site’s question bank: each worked example is recalculated by separate code, and each sample answer says where it came from.

The guide deliberately states no salaries, grades, pass marks or exam dates. Those change, and they could not be checked here, so take them from the advert itself.

This site is independent and is not affiliated with MIFOTRA or any employer.

Where to spend your study time

The suggested emphasis reflects what this position works with day to day. It is a study guide, not a published exam blueprint.

AreaSuggested emphasisQuestions in the bankPractise
Routing and switching 31%247Routing & Switching
Networking fundamentals 31%2,636Networking
Ports and protocols 15%264Networking
Cybersecurity 15%541Security
Fibre optics and cabling 8%1,221Fibre & Cabling

Facts that drive design decisions

Cabling limits decide where switches must sit and when fibre is needed between buildings. Private address ranges shape addressing plans and NAT design. The OSI model is the vocabulary for explaining where a problem lives and which device can fix it. When a design question mentions distance, address space or device placement, one of these tables usually holds the deciding fact.

Quick reference

The OSI model

LayerNameWhat happens hereExamples
7ApplicationServices the user’s software talks toHTTP, DNS, SMTP, SNMP
6PresentationData formatting, encoding and encryptionCharacter encoding, TLS
5SessionOpening, maintaining and closing sessionsSession setup and teardown
4TransportEnd-to-end delivery, ports, reliabilityTCP, UDP
3NetworkLogical addressing and routing between networksIPv4, IPv6, ICMP; routers
2Data linkFrames and physical (MAC) addressing on one linkEthernet, 802.11; switches
1PhysicalSignals on the mediumCopper, fibre, radio; connectors

Special IPv4 address ranges

RangePurpose
10.0.0.0/8Private addressing (RFC 1918)
172.16.0.0/12Private addressing (RFC 1918): 172.16.0.0 to 172.31.255.255
192.168.0.0/16Private addressing (RFC 1918)
100.64.0.0/10Carrier-grade NAT shared space (RFC 6598)
127.0.0.0/8Loopback
169.254.0.0/16Link-local (APIPA): a host that failed to get a DHCP lease

Common Ethernet cabling limits

CableTypical useDistance
Cat5e1 Gbps (1000BASE-T)100 m
Cat61 Gbps; 10 Gbps over short runs100 m at 1 Gbps; about 55 m at 10 Gbps
Cat6A10 Gbps (10GBASE-T)100 m
OM3 multimode fibre10GBASE-SRup to 300 m
OM4 multimode fibre10GBASE-SRup to 400 m
OS2 single-mode fibre10GBASE-LRup to 10 km

Networking terms

TermMeaning
ARPThe protocol resolving an IP address to a MAC address on a LAN
BandwidthThe maximum rate at which data can cross a link
Default gatewayThe router a host sends traffic to when the destination is off-subnet
FirewallA control that filters traffic against a rule set
JitterVariation in the delay between successive packets
LatencyThe delay between sending a packet and it arriving
Load balancerA device distributing requests across several backend servers
MAC addressA hardware address identifying an interface within a local network
NATTranslating private addresses to a public one at the network edge
OSI modelA seven-layer reference model for network communication
Packet lossPackets that never reach their destination
Proxy serverAn intermediary that makes requests on behalf of clients
RouterA device forwarding packets between different networks
SwitchA device forwarding frames between hosts inside one local network
TCPA connection-oriented transport that guarantees ordered delivery
UDPA connectionless transport with no delivery or ordering guarantee
VLANA logical broadcast domain separating traffic on shared switches
VPNAn encrypted tunnel carrying private traffic across a public network

Building a design vocabulary

Engineers need to use terms precisely, because design documents and conversations with vendors depend on shared meaning. The networking terms table includes words that appear both in exam questions and in real design discussions. For each term, make sure you can give a one-sentence definition and an example of where it matters.

Checks before the exam

  • State the order a router uses to choose a route.
  • Name the OSPF neighbour states in order.
  • Explain what hosts experience when the active HSRP router fails.
  • Give the maximum distance for Cat6A copper and for OS2 fibre at 10 Gbps.
  • Explain why summarisation needs contiguous subnets.
  • Describe the difference between eBGP and iBGP in one sentence.

Common questions

Are these tables enough to pass?

No. They hold facts that must be instant, but engineering questions test reasoning with those facts. Use the tables for quick recall and spend most of your time on scenarios and labs.

Why does cabling appear in a network engineer's reference?

Because physical limits constrain designs. A run longer than copper supports needs fibre, and that choice affects equipment, cost and installation.

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