Computer networks

1. Lesson Introduction

A computer network can contain many devices, cables, IP addresses, user accounts, servers, wireless access points, switches, routers, and security controls.

As a network grows, it becomes difficult to remember how everything is connected. Network documentation provides an organized record of the network so that technicians and administrators can understand, maintain, troubleshoot, secure, and improve it.

Good documentation answers questions such as:

• What devices are installed?

• Where is each device located?

• Which IP address belongs to each device?

• Which switch port is connected to a particular computer?

• Where does a network cable go?

• Which VLAN is assigned to a port?

• Which router connects to the Internet?

• What services are running?

• Who is responsible for the system?

• What changes have been made?

Network documentation is therefore an important part of professional network administration.

2. Learning Objectives

By the end of this lesson, the learner should be able to:

1. Define network documentation.

2. Explain why network documentation is important.

3. Identify different types of network documentation.

4. Create a basic network topology diagram.

5. Create a network device inventory.

6. Document IP addresses and subnets.

7. Document switch ports and cable connections.

8. Document VLAN information.

9. Record network configuration information safely.

10. Maintain network change records.

11. Create basic network troubleshooting documentation.

12. Explain how documentation supports network security.

13. Develop documentation for a small organization's network.

3. Meaning of Network Documentation

Network documentation is the organized recording of information about a computer network, its devices, configurations, connections, addresses, services, security controls, and changes.

It can exist in different forms, including:

• Network diagrams

• Device inventories

• IP address tables

• Cable records

• Configuration records

• VLAN tables

• Server documentation

• Wireless documentation

• Security documentation

• Maintenance records

• Change logs

• Troubleshooting records

4. Why Network Documentation Is Important

Network documentation helps an organization:

Troubleshoot Problems

A technician can quickly determine which device, cable, or network segment may be affected.

Maintain the Network

Documentation helps technicians understand existing configurations before making changes.

Reduce Downtime

Technicians can identify equipment and connections more quickly during failures.

Support Security

Administrators can identify authorized devices, network segments, and security controls.

Support Future Expansion

When adding computers, switches, access points, or servers, existing documentation helps determine where they should be connected.

Transfer Knowledge

If one technician leaves an organization, another technician can understand the network without starting from zero.

5. Network Topology Diagram

A network topology diagram shows how network devices are connected.

A simple diagram might show:

Internet
↓
Router
↓
Switch
├── PC 1
├── PC 2
├── Printer
└── Access Point

A more detailed diagram may include:

• Device names

• IP addresses

• VLANs

• Interfaces

• Cable types

• Port numbers

• Network segments

6. Physical Network Diagram

A physical network diagram shows the physical arrangement of network equipment.

It may document:

• Building

• Rooms

• Network racks

• Switches

• Routers

• Servers

• Access points

• Patch panels

• Cable routes

• Wall outlets

Example:

Server Room → Main Switch → Office 1
↓
Office 2
↓
Training Lab

7. Logical Network Diagram

A logical network diagram shows how the network is logically organized.

It may include:

• IP networks

• Subnets

• VLANs

• Routers

• Firewalls

• Logical connections

• Internet connections

Example:

VLAN 10 → Administration
VLAN 20 → Staff
VLAN 30 → Students
VLAN 40 → Guest Wi-Fi

A physical diagram answers:

"Where is the equipment?"

A logical diagram answers:

"How is the network organized?"

8. Network Device Inventory

A device inventory records information about network equipment.

Example:

Other information can include:

• Manufacturer

• Model

• MAC address

• Firmware version

• Purchase date

• Warranty

• Responsible technician

9. IP Address Documentation

Network administrators should maintain an accurate record of IP addresses.

Example:

IP documentation helps prevent:

• Duplicate IP addresses

• Incorrect gateway configuration

• Addressing confusion

• Troubleshooting delays

10. IP Address Management

IP Address Management, commonly called IPAM, is the organized management of IP address allocation and use.

An IPAM record can show:

• Available addresses

• Assigned addresses

• Reserved addresses

• Subnets

• DHCP ranges

• Static addresses

• Device names

For larger networks, dedicated IPAM systems may be used.

11. MAC Address Documentation

A MAC address is associated with a network interface.

Network administrators may document MAC addresses for important devices such as:

• Servers

• Routers

• Switches

• Access points

• Printers

• Network security devices

Example:

Device: AP-01
MAC: 00:11:22:33:44:55
IP: 192.168.10.20

MAC information can assist with troubleshooting and device identification.

12. Switch Port Documentation

Technicians should document what is connected to each switch port.

Example:

This makes troubleshooting much easier.

If PC-01 loses connectivity, the technician can immediately identify the relevant switch port.

13. Cable Documentation

Cable documentation records how network cables are installed.

Information may include:

• Cable ID

• Source

• Destination

• Patch panel port

• Switch port

• Cable type

• Location

• Status

Example:

Cable ID: C-015
Source: Office 3 wall outlet
Destination: Patch Panel Port 15
Switch Port: SW1 Fa0/15
Cable: Cat 6
Status: Active

14. Patch Panel Documentation

A patch panel provides an organized connection point for network cabling.

Documentation should identify which patch panel port connects to which room or outlet.

Example:

This is especially useful when troubleshooting structured cabling.

15. VLAN Documentation

Organizations using VLANs should document their VLAN structure.

Example:

Documentation should also identify:

• Access ports

• Trunk ports

• Inter-VLAN routing

• DHCP scopes

• Security rules

16. Wireless Network Documentation

Wireless documentation should record:

• Access point name

• Location

• IP address

• MAC address

• SSID

• VLAN

• Frequency/band configuration

• Management information

• Coverage area

• Installation date

Sensitive information such as Wi-Fi passwords should not be stored openly in ordinary documentation.

17. Server Documentation

Server documentation may include:

• Server name

• Server role

• IP address

• Operating system

• Hardware specifications

• Storage

• Applications

• Network interfaces

• Backup schedule

• Responsible administrator

Example:

Server: SRV-01
Role: File Server
IP: 192.168.10.20
Operating System: Windows Server
Storage: 2 TB
Backup: Daily

18. Network Configuration Documentation

Important configuration information should be documented.

Examples:

• Router configuration

• Switch configuration

• VLAN configuration

• Firewall rules

• DHCP configuration

• DNS configuration

• Wireless configuration

• VPN configuration

However, sensitive credentials such as administrator passwords should not simply be written into a normal network document.

19. Configuration Backups

Network device configurations should be backed up appropriately.

Devices that may require configuration backups include:

• Routers

• Switches

• Firewalls

• Wireless controllers

• Access points

Configuration backups can help restore services after:

• Hardware failure

• Incorrect configuration

• Accidental deletion

• Cybersecurity incident

• Device replacement

20. Change Management Documentation

Networks change over time.

Examples include:

• Installing a new switch

• Changing an IP address

• Creating a VLAN

• Replacing a router

• Updating firewall rules

• Adding an access point

• Moving a server

Each significant change should be recorded.

Example:

Date: 7 October 2026
Device: SW1
Change: Added VLAN 30
Reason: Separate student computers from staff devices
Technician: Network Administrator
Result: Successful

21. Change Log

A change log provides a history of modifications.

Change records help identify when a problem started.

22. Maintenance Records

Network maintenance should also be documented.

Record:

• Date

• Device

• Maintenance performed

• Technician

• Problems found

• Parts replaced

• Result

• Next maintenance date

Example:

Device: UPS-01
Maintenance: Battery inspection
Result: Battery requires replacement
Action: Replacement scheduled

23. Incident Documentation

Security and network incidents should be recorded.

Examples:

• Malware infection

• Unauthorized access

• Network outage

• Hardware failure

• Configuration error

• Unauthorized device

• Suspicious traffic

Incident records should contain appropriate information such as:

• Date and time

• Affected systems

• Description

• Initial symptoms

• Actions taken

• Recovery

• Root cause, if known

• Preventive action

24. Troubleshooting Documentation

Technicians should record troubleshooting procedures and results.

Example:

Problem: Computer cannot access Internet.

Steps:

1. Checked physical cable.

2. Checked link light.

3. Checked IP configuration.

4. Tested gateway.

5. Tested DNS.

6. Checked switch port.

7. Found faulty cable.

8. Replaced cable.

9. Connectivity restored.

This information can help if the same problem occurs again.

25. Network Documentation and Security

Network documentation itself must be protected.

Some documentation can contain sensitive information such as:

• Internal IP addresses

• Firewall rules

• Device management addresses

• Network diagrams

• Server information

• Security configurations

Therefore:

• Restrict access.

• Protect files with appropriate permissions.

• Store backups securely.

• Avoid exposing sensitive information publicly.

• Do not place passwords in ordinary network diagrams.

• Maintain appropriate version control.

26. Documentation Standards

Good network documentation should be:

Accurate

Information must reflect the actual network.

Current

Update documents whenever important changes occur.

Clear

Use understandable names and descriptions.

Consistent

Use the same naming conventions throughout the documentation.

Organized

Separate documents into logical categories.

Secure

Restrict access to sensitive information.

Accessible

Authorized technicians should be able to find the information when needed.

27. Device Naming Conventions

Consistent naming makes documentation easier.

Examples:

RTR-01 → Router 1
SW-01 → Switch 1
AP-01 → Access Point 1
SRV-01 → Server 1
PC-LAB1-01 → Lab 1 Computer 1
PRN-OFF-01 → Office Printer 1

Organizations should establish a naming convention and use it consistently.

28. Network Documentation Example

Consider a training centre with:

• 20 computers

• 2 switches

• 1 router

• 3 access points

• 1 server

• 2 printers

A basic documentation package could contain:

1. Network topology diagram.

2. Device inventory.

3. IP address table.

4. VLAN table.

5. Switch port map.

6. Cable schedule.

7. Wireless AP list.

8. Server information.

9. Configuration backup records.

10. Maintenance records.

11. Change log.

12. Incident records.

29. Example Network Documentation Package

Network Information

Network: Training Centre LAN
Main subnet: 192.168.10.0/24
Gateway: 192.168.10.1
DNS: Organization-approved DNS service

Devices

RTR-01 → Router
SW-01 → Main switch
SW-02 → Secondary switch
SRV-01 → Server
AP-01 → Training Lab
AP-02 → Staff Area
AP-03 → Reception

VLANs

VLAN 10 → Administration
VLAN 20 → Staff
VLAN 30 → Students
VLAN 40 → Guests

30. Practical Activity 1: Create a Device Inventory

Learners should identify at least ten network devices or endpoints in a laboratory.

Record:

• Device name

• Device type

• Location

• IP address

• MAC address

• Status

• Responsible person

31. Practical Activity 2: Draw a Network Diagram

Draw a network containing:

• Internet

• Router

• Firewall

• Switch

• Four PCs

• Server

• Printer

• Wireless access point

Label the major connections.

32. Practical Activity 3: Create an IP Address Table

Create an IP addressing table for the network.

Include:

• Device

• IP address

• Subnet mask

• Gateway

• VLAN

• Status

33. Practical Activity 4: Document Switch Ports

Inspect a switch or simulated switch and document:

• Switch name

• Port number

• Connected device

• VLAN

• Port status

34. Practical Activity 5: Create a Change Record

Simulate the following change:

"Add a new access point to the training laboratory."

Document:

• Date

• Technician

• Device name

• IP address

• Switch port

• VLAN

• Reason

• Result

35. Practical Activity 6: Troubleshooting Record

Simulate a network outage.

Document:

1. Reported problem.

2. Time reported.

3. Affected users.

4. Tests performed.

5. Cause identified.

6. Corrective action.

7. Restoration time.

8. Recommended preventive action.

36. Assessment Questions

1. What is network documentation?

2. Why is network documentation important?

3. What is a network topology diagram?

4. Differentiate physical and logical network diagrams.

5. What information should be included in a device inventory?

6. Why should IP addresses be documented?

7. What is IP address management?

8. Why is switch port documentation useful?

9. What information should be included in cable documentation?

10. What is VLAN documentation?

11. Why should wireless access points be documented?

12. What is a change log?

13. Why should network configurations be backed up?

14. What information should be recorded after a network incident?

15. Why should network documentation be protected?

16. What is a device naming convention?

17. Give five examples of network documents.

18. Explain why documentation should be kept up to date.

19. What is the difference between a network diagram and a device inventory?

20. Explain how documentation helps troubleshoot network problems.

37. Assignment

A new computer training centre has:

• 30 computers

• 2 switches

• 1 router

• 1 firewall

• 3 wireless access points

• 2 servers

• 2 network printers

Prepare a complete basic network documentation package.

Your submission should include:

1. Physical network diagram.

2. Logical network diagram.

3. Device inventory.

4. IP addressing table.

5. VLAN table.

6. Switch port table.

7. Cable schedule.

8. Wireless access point table.

9. Server information.

10. Maintenance schedule.

11. Change log.

12. Network security information.

Do not include actual administrator passwords or other highly sensitive credentials in the submitted documentation.

38. Key Terms

• Network documentation

• Network diagram

• Physical topology

• Logical topology

• Device inventory

• IP address management

• MAC address

• VLAN

• Switch port

• Patch panel

• Cable schedule

• Server documentation

• Configuration backup

• Change management

• Change log

• Maintenance record

• Incident record

• Troubleshooting record

• Naming convention

• Network administrator

39. Lesson Summary

Network documentation provides a structured record of how a network is designed, configured, connected, maintained, and secured.

Important documentation includes:

• Network diagrams

• Device inventories

• IP address records

• VLAN tables

• Switch port maps

• Cable schedules

• Wireless documentation

• Server records

• Configuration backups

• Change logs

• Maintenance records

• Incident records

• Troubleshooting records

Good documentation should be accurate, current, clear, consistent, organized, secure, and accessible to authorized personnel.

A well-documented network is easier to troubleshoot, maintain, secure, expand, and hand over to another technician.

42. Senior ICT Academy Campus

More learning will be delivered through Senior ICT Academy Campus by either a physical instructor or an online instructor.

Learners can use practical sessions to create network diagrams, document real or simulated network devices, prepare IP address tables, record switch ports, and develop professional troubleshooting records.

Campus: https://campus.seniorictacademy.com/

43. Final Practical Challenge

Create a complete network documentation file for a simulated organization.

The organization has:

• Internet connection

• One router

• One firewall

• Two switches

• One server

• Ten computers

• Two printers

• Two wireless access points

Prepare:

1. Physical network diagram.

2. Logical network diagram.

3. Device inventory.

4. IP address table.

5. VLAN table.

6. Switch port map.

7. Cable schedule.

8. Wireless AP documentation.

9. Maintenance record.

10. Change log.

11. Troubleshooting record.

The final documentation should be clear enough that another network technician can understand the network and troubleshoot a basic connectivity problem without needing to ask the original technician for additional information.