What are the main building blocks of an enterprise campus network?
Show the answer
Say this first
Distribution blocks (access plus distribution for each building or floor group), the campus core, a server or data center block, a WAN edge for branches and other sites, an internet edge with firewalls and a DMZ, a shared services block (DNS, DHCP, RADIUS, wireless controllers) and a management network. Each block has one job and connects to the core, so you can change one without redesigning the others.
Go deeper
| Block | What lives there | Design focus |
|---|---|---|
| Access and distribution | Users, phones, APs, IoT | Port density, PoE, edge security, gateway failover |
| Core | Only interconnects | Speed, redundancy, simplicity |
| Data center or server block | Servers, storage, virtualization hosts | Bandwidth, low oversubscription, east-west security |
| WAN edge | Routers or SD-WAN edges to branches and other sites | Routing policy, QoS, encryption |
| Internet edge | Edge routers, firewalls, DMZ, remote access VPN | Security, dual ISP, NAT |
| Services | DNS, DHCP, RADIUS or ISE, wireless controllers, NTP | Availability, reachable from everywhere |
| Management | Out-of-band network, monitoring, jump hosts | Reachable when production is broken |
Why this matters in the interview
When you are asked to design anything, naming the blocks first shows structure. Then you size and secure each one. The blocks also map to failure domains: an internet edge problem should not take down internal routing.
Traps
- Forgetting the management network. Interviewers often follow up with how you reach devices when the network is down.
How did you do?Book 1.2 Requirements