CCNA in 10 Weeks

200-301 v1.1

Fundamentals

Network Topologies

CCNA expects you to separate physical topology (how cables and devices are laid out) from logical topology (how data actually flows). They are not always the same — the classic example is a physical star with a hub, which is a logical bus.

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Quick exam reference

PhysicalLogicalCentral device / medium
Star (switch)StarSwitch
Star (hub)BusHub
BusBusShared coax / backbone
Point-to-pointPoint-to-pointSerial / routed link

Physical star / logical star (switch)

CCNA core

Modern LAN default — each host has a dedicated link to a switch.

Physical starLogical starSWSame cabling as hub star — different central deviceSWunicastSwitch forwards only to destination port

Physical topology

Every endpoint connects to a central switch.

  • •Dedicated links — no shared medium between hosts.
  • •A switch failure isolates only directly attached devices if redundant paths are absent.

Logical topology

Traffic is switched only to the intended destination port.

  • •Unlike a hub, collisions are not propagated domain-wide.
  • •Broadcasts still flood the VLAN unless segmented.

CCNA tip: When a question shows a switch in the center, assume logical star switching.

Real world: Office access layers almost always use switched stars.

Physical bus / logical bus

Common on exam

Legacy shared-medium layout — still appears on fundamentals questions.

PhysicalLogicalTermShared coax backboneSingle collision domainAll stations share one medium (CSMA/CD)Logical bus — same as physical

Physical topology

Hosts attach to one continuous cable segment.

  • •Terminators at both ends prevent signal reflection.
  • •A break in the cable can affect the entire segment.

Logical topology

All stations hear every frame on the shared medium.

  • •Classic CSMA/CD Ethernet behavior on coax.
  • •Hub-based stars are physically star but logically bus.

CCNA tip: Hub = physical star, logical bus is a favorite trick question.

Real world: Rare in modern LANs; concept still explains collision domains.

Point-to-point

CCNA core

Single link between two endpoints — common on WAN diagrams.

Physical P2PLogical P2PR1R2Serial / WANOne cable, two endpoints — no shared segmentR1R2PPP / HDLCDedicated path — only these two devices

Physical topology

Exactly two devices connected by one link.

  • •Serial, fiber, or routed Ethernet handoff between two routers.
  • •No third device shares the medium.

Logical topology

Traffic has only one possible egress path.

  • •Often drawn as a line between router icons on exam topology maps.
  • •May carry many routed subnets — still one logical hop.

CCNA tip: Label WAN links as point-to-point even when the drawing is minimal.

Real world: Site-to-site VPN overlays still model as logical point-to-point tunnels.

How to read exam diagrams

  • Identify the center device first: hub → likely logical bus; switch → logical star.
  • WAN questions often use point-to-point, partial mesh, or hub-and-spoke — LAN questions focus on bus, star, and ring.
  • Hybrid networks are normal. Label each segment separately instead of forcing one topology name on the entire drawing.