Lesson 4: Network Services and SOHO Design Lab

Core path: 42 minutes

A small network depends on more than a router and Wi-Fi password. Today you map the services and configuration objects that make the user experience work.

Fictional training center

Requirements:

• 24 wireless laptops;
• 4 wired desktops;
• shared network printer;
• staff and guest logical separation;
• local file share;
• centralized authentication/accounting service in the scenario;
• web and database-backed application;
• time synchronization;
• mail service protected by spam filtering;
• remote staff VPN access.

Part A: host/service roles

Map these roles to a purpose:

• DNS;
• DHCP;
• file share;
• print server;
• mail server;
• syslog;
• web server;
• AAA;
• database server;
• NTP.

Then recognize these appliances/systems:

• spam gateway;
• UTM;
• load balancer;
• proxy;
• SCADA as a legacy/embedded operational-system category;
• IoT endpoints.

The goal is recognition and architecture, not administering real infrastructure.

Part B: configuration

Design:

DHCP scope:
reservation:
exclusion:
DNS A/AAAA/CNAME/MX/TXT use:
DKIM/SPF/DMARC recognition:
staff VLAN:
guest VLAN:
VPN use case:
default gateway/NAT path:

Part C: wireless design

Choose band/channel strategy for the two APs using supplied fictional neighboring-network data. State channel width, band, security mode, and one interference tradeoff.

Fault injection

Choose three:

• DHCP scope exhausted;
• wrong DNS record;
• guest client placed in staff VLAN expectation incorrectly;
• VPN unavailable while local service remains healthy;
• NTP service unavailable causing time drift across fictional clients;
• proxy configuration blocks one web path;
• strong Wi-Fi association but AP uplink fails.

Deliverable

For each fault record:

user symptom:
service/configuration involved:
what still works:
failed boundary:
next evidence:
verification after correction:

Success criteria

A passing design connects ports/protocols, wireless technology, service roles, DNS/DHCP records, VLANs, and VPN into one supportable SOHO system.