CompTIA A+ / Network+ / Security+ CompTIA Network+: Networking Concepts & Models (N10-009) Syllabus

CompTIA Network+: Networking Concepts & Models (N10-009) syllabus: all 5 chapters

Expand any chapter to see its topics and sub-topics.

1. 1

   OSI and Networking Models

   3 topics

   • The Seven-Layer OSI Model
     • Layer functions from physical to application
     • Encapsulation and de-encapsulation
   • TCP/IP Model and Protocol Data Units
     • Frames, packets, segments and data
     • Mapping TCP/IP to OSI
   • Network Topologies and Architectures
     • Star, mesh, hybrid and spine-and-leaf
     • Three-tier and collapsed-core designs
     • Traffic flows: north-south and east-west
2. 2

   Cabling, Connectivity and Media

   3 topics

   • Copper and Fibre Media
     • Twisted pair categories and shielding
     • Single-mode versus multi-mode fibre
   • Connectors and Transceivers
     • RJ45, LC, SC, MPO and BNC
     • SFP, SFP+, QSFP and media converters
   • Termination Standards and Tools
     • T568A and T568B wiring
     • Cable testers, OTDR and crimpers
3. 3

   IP Addressing and Subnetting

   4 topics

   • IPv4 Addressing
     • Classful, classless and CIDR notation
     • Public, private and APIPA ranges
   • Subnetting and VLSM
     • Calculating subnets, hosts and broadcast addresses
     • Variable-length subnet masking and supernetting
   • IPv6 Addressing
     • Address types: global unicast, link-local, multicast
     • SLAAC, EUI-64 and dual stack
   • Network Address Translation
     • Static NAT, dynamic NAT and PAT/overload
4. 4

   Network Services and Applications

   3 topics

   • Core Network Services
     • DHCP scopes, reservations and relay
     • DNS record types: A, AAAA, CNAME, MX, PTR, TXT, SRV
     • NTP and time synchronisation
   • Ports and Protocols Reference
     • Well-known, registered and dynamic port ranges
     • Secure versus insecure protocol pairs
   • Network Architecture Services
     • Load balancers, proxies and content delivery networks
5. 5

   Cloud and Datacentre Concepts

   3 topics

   • Cloud Deployment and Service Models
     • IaaS, PaaS, SaaS and the responsibility matrix
     • Public, private, hybrid and multi-cloud
   • Cloud Connectivity and Networking
     • Virtual private cloud, subnets and gateways
     • Direct connect and VPN to cloud
   • Network Function Virtualisation
     • Virtual switches, routers and firewalls

CompTIA A+ / Network+ / Security+ CompTIA Network+: Networking Concepts & Models (N10-009) flashcards — 51 questions with answers

1. List the seven layers of the OSI model in order from Layer 1 to Layer 7.

   Layer 1 Physical, Layer 2 Data Link, Layer 3 Network, Layer 4 Transport, Layer 5 Session, Layer 6 Presentation, Layer 7 Application. A common mnemonic is 'Please Do Not Throw Sausage Pizza Away'.

2. At which OSI layer do routers operate and what addressing do they use?

   Routers operate at Layer 3 (Network) and use logical IP addresses to make forwarding/path-selection decisions between networks.

3. What is the Protocol Data Unit (PDU) name at each of these layers: Transport, Network, Data Link, Physical?

   Transport = Segment (TCP) or Datagram (UDP); Network = Packet; Data Link = Frame; Physical = Bits.

4. Which OSI layer is responsible for MAC addressing, framing, and error detection via the FCS, and what are its two sublayers?

   Layer 2, the Data Link layer. Its two sublayers are the LLC (Logical Link Control) and the MAC (Media Access Control).

5. How do the four layers of the TCP/IP model map to the seven OSI layers?

   Network Access/Link = OSI Physical + Data Link; Internet = OSI Network; Transport = OSI Transport; Application = OSI Session + Presentation + Application.

6. What is the OSI Layer 4 difference between TCP and UDP?

   TCP is connection-oriented, reliable, sequenced, and uses a three-way handshake with acknowledgements and flow/congestion control. UDP is connectionless, best-effort, unsequenced, with lower overhead and latency.

7. What three steps make up the TCP three-way handshake?

   1) SYN (client to server), 2) SYN-ACK (server to client), 3) ACK (client to server). The connection is then established.

8. Which OSI layer handles encryption, compression, and data format translation (e.g., ASCII, JPEG, SSL/TLS presentation)?

   Layer 6, the Presentation layer.

9. Define a star, mesh, and bus physical topology.

   Star: every node connects to a central switch/hub (most common in modern LANs). Mesh: nodes interconnect with multiple/redundant paths (full mesh = every node to every node). Bus: all nodes share a single backbone cable.

10. In a full-mesh network of $n$ nodes, how many direct links are required?

    $\frac{n(n-1)}{2}$ links.

11. What is the difference between a three-tier and a spine-and-leaf data-centre architecture?

    Three-tier uses core, distribution (aggregation), and access layers, optimized for north-south traffic. Spine-and-leaf is a two-tier design where every leaf connects to every spine, optimized for low-latency east-west traffic with predictable hop counts.

12. Compare single-mode fibre (SMF) and multimode fibre (MMF).

    SMF has a small core (about $9\,\mu m$), uses laser light, supports long distances (km) and high bandwidth, typically yellow jacket. MMF has a larger core ($50/62.5\,\mu m$), uses LED/VCSEL, supports shorter distances (hundreds of metres), typically aqua/orange jacket.

13. What does the category rating of twisted-pair copper (Cat 5e, Cat 6, Cat 6a) determine, and what speed/distance does Cat 6a support?

    The category rating determines bandwidth/frequency and supported speed. Cat 6a supports 10GBASE-T (10 Gbps) up to 100 m, at 500 MHz.

14. What is the difference between UTP and STP copper cabling?

    UTP (Unshielded Twisted Pair) relies only on the twist to cancel interference. STP (Shielded Twisted Pair) adds metallic shielding (foil/braid) around pairs or the whole cable to reduce EMI/crosstalk, requiring proper grounding.

15. What is the maximum standard cable run length for copper Ethernet (twisted pair) and why?

    100 metres (90 m of solid horizontal cable plus 10 m of patch cords). Beyond this, attenuation and signal degradation make reliable communication unlikely.

16. Match these fibre connectors to their description: LC, SC, ST, MPO.

    LC = small form-factor (little/Lucent connector), push-pull latch, common in high density. SC = square 'subscriber/standard' push-pull connector. ST = round bayonet 'straight tip' twist-lock. MPO = multi-fibre push-on, carries many fibres (e.g., 12/24) for 40/100G.

17. What is a transceiver, and what do the SFP, SFP+, QSFP, and QSFP28 form factors typically support?

    A transceiver is a hot-swappable module that converts between electrical and optical (or copper) signals. SFP supports up to 1 Gbps, SFP+ up to 10 Gbps, QSFP up to 40 Gbps (4x10G), and QSFP28 up to 100 Gbps.

18. What are the pin assignments difference between T568A and T568B wiring standards?

    They differ by swapping the green and orange pairs. T568B (most common in the US) order: white-orange, orange, white-green, blue, white-blue, green, white-brown, brown. T568A swaps orange and green pairs. Both ends matching makes a straight-through cable.

19. What tools are used to terminate, attach, and test copper cabling: punchdown, crimper, cable tester, TDR?

    Punchdown tool seats wires into 66/110 blocks or keystone jacks. Crimper attaches RJ45 connectors to cable. Cable tester verifies continuity/wiremap. A TDR (Time-Domain Reflectometer) locates cable faults/breaks by distance.

20. What are the three default classful IPv4 address ranges (Class A, B, C) by first octet?

    Class A: 1–126 (default mask /8). Class B: 128–191 (default mask /16). Class C: 192–223 (default mask /24). 127 is reserved for loopback.

CompTIA A+ / Network+ / Security+ CompTIA Network+: Networking Concepts & Models (N10-009) FAQ