A checklist for building a site

Under exam pressure it's easy to forget a step. Build every site in the same order, bottom up, and each layer rests on a working one below:

1. Physical / interfaces. Cable, no shutdown, addresses. Check show ip interface brief: up/up.
2. Switching. VLANs, access ports, trunks. show vlan brief, show interfaces trunk.
3. Routing. Static or OSPF so every subnet is reachable. show ip route, ping end to end.
4. Services. DHCP, NAT, DNS, NTP as needed. Test from a client.
5. Security. SSH, passwords, ACLs, port security - last, so you don't lock yourself out mid-build.
6. Save. copy running-config startup-config.

The matching troubleshooting order is the same, bottom up: a service can't work if routing is broken, and routing can't work if an interface is down. Always check the layer below before blaming the one above.

Remember: Interfaces → switching → routing → services → security → save. Troubleshoot bottom up.