Installing, Configuring, and Troubleshooting the Network Infrastructure
Core mechanics
This domain is hands-on: interface configuration, addressing, routing, name resolution, and the tools that prove each layer works. A candidate must be able to read an IP configuration and state immediately whether the host can reach its gateway, and to interpret ping, tracert/traceroute, ipconfig/ifconfig, arp, route print, and nslookup output. Understand static versus dynamic addressing, DHCP scope options (gateway, DNS, lease duration), and why a mis-scoped option breaks clients that otherwise have valid addresses.
Layered troubleshooting
Work bottom-up or top-down consistently. Physical/link first (cable, duplex, speed mismatch, VLAN assignment on the switch port), then addressing, then routing, then name resolution, then application. Recognise symptoms: an APIPA address (169.254.x.x) means no DHCP response; a correct address but failed pings to the gateway suggests VLAN or switch-port issues; pings by IP succeeding while names fail points at DNS.
Traps
Questions often present a symptom and offer a fix at the wrong layer - e.g., re-adding a DNS server when the real fault is a missing default gateway. Another trap is confusing a link-local address with a routable one, or assuming a successful ping proves the service is healthy (it only proves ICMP reachability). Duplex/speed autonegotiation mismatches still appear as "intermittent slowness" distractors.
Worked example
A workstation reports 169.254.10.5. It can ping nothing beyond itself. The fault is DHCP reachability, not DNS and not the gateway. Check the switch port's VLAN, the DHCP relay on that subnet, and scope exhaustion - in that order - before touching the client.
Also know
Interface naming conventions, static route syntax, and how to verify a change without rebooting the device.