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CompTIA Network+ N10-009 · Objective 1.1 · Block 1 of 4

Follow a connection through the OSI layers

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Carries individual bits as electrical, optical, or radio signals over cables or wireless media; it does not interpret frames or addresses.

Answer choices
Four layers, four different jobs
Layer 4 · Transport
Between applicationsTCP or UDP ports identify the applications. TCP adds reliable, ordered delivery.
Layer 3 · Network
Between IP networksRouters read destination IP addresses and select routes for packets.
Layer 2 · Data link
Across the local networkEthernet switches use destination MAC addresses to forward frames.
Layer 1 · Physical
Across a mediumElectrical, optical, or radio signals carry individual bits.
Read downward: delivery between applications depends on an IP path, local frame forwarding, and physical signals. These are the four lower OSI layers taught in this block.
Concept notes

Physical layer

Carries individual bits as electrical, optical, or radio signals over cables or wireless media; it does not interpret frames or addresses.

Data link layer

Forwards frames between devices on the same local network by having Ethernet switches read destination MAC addresses.

Network layer

Forwards packets from one IP network to another as routers read destination IP addresses and consult routing tables.

Transport layer

Uses TCP or UDP port numbers to deliver data between applications on different hosts; TCP also provides reliable ordered delivery and flow control.

Continue into the full block check

4 questions · Pass with 3 of 4 correct · feedback after each answer

This records your study. Passing the check is still required for course progress.
CompTIA Network+ · Objective 2.2 · Switch terminal · 5 minPlace a printer in its VLAN
Open terminal practice

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