A structured lesson workspace with readable content, hands-on examples, and a clean path to completion.
Bank with 30 branches: half on old T1 for card readers, half on fiber. HQ wants 5-year plan. Nightly backups can use cheap internet. Card payments need low jitter. Same bank, two different WAN answers. This lesson teaches you to choose.
| Scope | Size | Example kit | Main worry |
|---|---|---|---|
| Home/SOHO | 1-20 users | ISP router + AP | Simplicity |
| Branch | 20-150 users | Switch + router + AP | Cost per port, which WAN |
| Campus | 500+ users | Collapsed-core switches | Redundancy, segmentation |
| Provider | City/country | Carrier core, BGP | Scale, SLA |
LAN = you own it, microseconds, private addresses. WAN = someone else runs it, you rent it, 5-200 ms. WiFi = LAN over radio. Cloud = WAN you reach via VPN/API. That's enough for now.
CCNA rule: real-time (voice, trading feed) -> MPLS or SD-WAN with SLA. Bulk (backups) -> internet VPN is fine. Exam tests choice, not carrier config. Full depth in Module 17.
Underlay = physical circuits (fiber, MPLS, LTE). Overlay = logical network on top (VPN, SD-WAN tunnels). Overlay lets you switch carriers without rewriting firewall rules. Remember: underlay carries, overlay decides.
Market-data app needs sub-15 ms to DC. Broadband jitters, ticks missed. Money matters less than uptime. Choice?
Select the safest next action.
Module 1 done. You can map any home/branch, measure it, and triage like helpdesk L1. Module 2 goes hands-on with frames and switches.
Finish the lesson once you have worked through the material. This awards ★ 55 XP.