RANGER CompTIA Network+ (N10-009) · chapter 11 of 29
Week 11: Map the territory
In this chapter Objectives 3.1
Objective 3.1
Network documentation
Physical vs. logical diagrams
A physical diagram shows where things really are: which closet, which rack, which cable runs to which jack. A logical diagram shows how traffic flows: subnets, VLANs, routing, which device is the default gateway. Same network, two views. A tech pulling cable needs the physical one; an engineer planning a new VLAN needs the logical one.
Exam tip Trap: 'which jack goes to which patch panel port' is physical. 'Which subnet is the warehouse on' is logical.
Network diagrams by layer
CompTIA also names diagrams by OSI layer.
- Layer 1: cables, ports, media, patch panels (the physical paths)
- Layer 2: switches, VLANs, trunks, MAC-level links, spanning tree
- Layer 3: routers, subnets, IP addresses, routing and gateways
Exam tip Ask what the diagram labels: cable runs = L1, VLANs and trunks = L2, subnets and routes = L3.
Rack diagrams and cable maps
A rack diagram shows each device's position in the rack by rack unit (U), front and back, plus power. A cable map (cable diagram) lists every run end to end: wall jack, patch panel port, switch port, label. Good labels on BOTH ends of every cable turn a two-hour hunt into a two-minute fix.
RACK HQ-MDF-R1 (42U) U42-41 Patch panel PP1 (48 port) U40 Cable manager U39-38 Core switch HQ-CORE1 U37 Firewall FW1 U20-17 Server ESX1 U02-01 UPS-1 (2U)
Asset inventory
An asset inventory lists what you own so nothing is forgotten, lost or left unpatched. CompTIA lists four things to track:
- Hardware: model, serial number, location, owner
- Software: what runs where, including versions
- Licensing: how many seats you own vs. use, renewal dates
- Warranty support: coverage end dates and support contracts
Exam tip An expired warranty or support contract is a business risk: no RMA, no vendor help during an outage.
IPAM
IP address management (IPAM) tracks your address space: which subnets exist, which addresses are used, reserved or free, and often ties into DHCP and DNS. It prevents duplicate IPs and shows when a scope is nearly full.
Exam tip Spreadsheets drift. IPAM tools pull live data from DHCP/DNS so the plan matches reality.
SLA
A service-level agreement (SLA) is a contract that defines the service a provider must deliver: uptime (like 99.9%), response and repair times, and penalties if they miss. Kibble's ISP circuit has one, and so does IT's promise to the stores.
Exam tip 99.9% uptime still allows about 8.8 hours of downtime a year. 99.99% allows about 53 minutes.
Wireless survey and heat map
A wireless site survey measures real signal strength, noise and interference around a building. The result is usually a heat map: a floor plan colored by signal strength, showing dead spots and overlap. Do one before installing APs (predictive or on-site) and after, to verify coverage.
Exam tip Heat map = picture of coverage. It is the go-to document when users say 'Wi-Fi is bad over by dock 4'.
Check yourself 1Dev wants a document showing which VLANs exist and which switch trunks carry them. Which diagram fits best?
- Layer 1 network diagram
- Rack diagram
- Layer 2 network diagram
- Wireless heat map
Show the answer
Answer: C. Layer 2 network diagram
VLANs and trunks are Layer 2 ideas, so a Layer 2 diagram shows them. A Layer 1 diagram shows cables and ports, not VLANs.
Practice questions
Answer in your head, then open the answer. Ranger's Packet Trail has 483 questions like these for Network+, with mock exams.
Question 1A new technician must find which wall jack in room 214 connects to which patch panel port and which wall it runs through. Which document should they open?
- Service-level agreement
- IP address management report
- Logical network diagram
- Physical network diagram
Show the answer
Answer: D. Physical network diagram
A physical diagram shows where devices, cable runs, jacks and racks really are. A logical diagram shows how traffic flows (subnets, VLANs, routing), not where cables run.
Question 2Which diagram would BEST show that VLAN 20 uses subnet 10.20.0.0/24 and is routed through the core switch's SVI?
- Logical network diagram
- Rack diagram
- Physical network diagram
- Cable map
Show the answer
Answer: A. Logical network diagram
Logical diagrams show VLANs, IP subnets and how traffic is routed. Physical diagrams and rack diagrams show where hardware and cables are located.
Question 3A data center tech needs to know that the firewall sits in units 30-31 of cabinet B4, directly above the patch panel. Which document shows this?
- Asset inventory
- Wireless heat map
- Rack diagram
- Layer 3 network diagram
Show the answer
Answer: C. Rack diagram
A rack diagram (rack elevation) shows each device's position in a rack by rack unit (U). A Layer 3 diagram shows routing and subnets.
Question 4An engineer is drawing a network diagram that shows only switches, the trunk links between them and which VLANs each trunk carries. No IP addresses are shown. Which type of diagram is this?
- Rack diagram
- Layer 3 diagram
- Layer 2 diagram
- Layer 1 diagram
Show the answer
Answer: C. Layer 2 diagram
Layer 2 diagrams show switching: switches, trunks, VLANs and STP. Layer 3 diagrams add IP subnets and routing; Layer 1 shows physical cabling and media.
Question 5A manager asks which access switches will lose vendor hardware support next year so they can budget replacements. Which record should the network team check FIRST?
- Wireless site survey report
- Change request tracking log
- Baseline configuration
- Asset inventory (warranty data)
Show the answer
Answer: D. Asset inventory (warranty data)
An asset inventory tracks hardware, software, licensing and warranty/support details for each device. Baseline configs describe settings, not support contracts.
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